Silicea — pure flint, also written Silica and given in the old texts as Silicea terra — is the remedy of what will not resolve. The abscess that never quite ripens or never quite closes. The splinter the body cannot expel. The fracture that will not knit, the scar that hardens, the child who does not thrive. Where other remedies act on the acute event, Silicea acts on the process that has stalled.
Boericke opens with the mechanism: "imperfect assimilation and consequent defective nutrition. It goes further and produces neurasthenic states in consequence, and increased susceptibility to nervous stimuli and exaggerated reflexes." Everything else follows from that — the weak bones, the poor healing, the chilliness, the exhaustion, and the peculiar combination of a sharp mind housed in a body that cannot keep up with it.
The remedy's most quoted phrase is also Boericke's, and it is a pun on the source: "want of grit, moral or physical." Flint is grit; the Silicea patient has none. This guide profiles the remedy for clinical study from Boericke's Materia Medica, Clarke's Dictionary, Boger's Synoptic Key and Lippe's Keynotes. The originals can be read in full — Clarke's Silicea, Boericke's Silicea and Kent's Silicea — through Similia's free digital materia medica.
The Silicea Constitutional Type
Boericke's constitutional sketch centres on the child: "scrofulous, rachitic children, with large head, open fontanelles and sutures, distended abdomen, slow in walking." Boger gives the same picture in three strokes — "large head, with wasted body," "big, hard or hot belly; with thin legs," and "arrested development. Late learning to walk."
The adult carries the same signature forward. The build is fine and undernourished; the complexion is, in Boger's words, "fair, clear," or in Boericke's, "delicate, pale, waxy." The nails are a reliable place to look: Boericke lists "affections of finger nails, especially if white spots on nails," along with crippled and ingrowing nails.
Thermally the type is unmistakable. Boericke: "Silica patient is cold, chilly, hugs the fire, wants plenty warm clothing, hates drafts, hands and feet cold, worse in winter. Lack of vital heat." Boger's version — "hugs the stove" — makes the same point. Great sensitivity to taking cold runs alongside it, and Lippe adds the specific causation: "he catches cold easily, especially when he uncovers his feet and head."
Two further constitutional markers matter. First, intolerance of alcoholic stimulants — Lippe notes "congestion and thirst after drinking but little wine." Second, the ill effects of vaccination, which Boericke italicises and which remains one of the classical indications for the remedy.
Mental and Emotional Picture
Yielding and faint-hearted. Boericke's mental keynote is a short list: "yielding, faint-hearted, anxious. Nervous and excitable. Sensitive to all impressions." The Silicea patient anticipates failure. Faced with a task — an examination, a performance, a difficult conversation — they are convinced in advance that they will not manage, and their anxiety is anticipatory rather than retrospective.
Yet obstinate. The apparent contradiction is genuine and is recorded in both sources. Boericke lists "obstinate, headstrong children" a line after "yielding"; Boger writes "lacks grit" and, a few words later, "sullen and stubborn." The resolution is that the Silicea patient lacks confidence but not will. They will not push forward, but they can be immovable about not being pushed.
Mental acuteness with physical weakness. Boger states it plainly: "mental acuteness, with physical weakness or torpidity." Intellect is intact and often sharp; the body and the nerve force will not sustain it. Boericke's "brain-fag" and "prostration of mind and body" describe what happens when the patient tries.
Sensitivity to stimuli. Boger capitalises it: "KEENLY SENSITIVE; to noise, pain or cold," and adds sensitivity to nervous excitement, light, and jarring of the spine. Boericke notes aversion to light, "especially daylight," and sensitivity to noise with roaring in the ears.
Fixed ideas. The remedy's most singular mental symptom, from Boericke: "fixed ideas; thinks only of pins, fears them, searches and counts them." Rare in practice, but so specific that its presence is close to decisive.
Somnambulism. Boericke records "night-walking; gets up while asleep," with frequent starts in sleep and anxious dreams; Boger confirms "somnambulism" and "frightful dreams, wake him on falling to sleep."
Physical Affinities
Suppuration. This is the remedy's defining pathology. Boericke: "suppurative processes... it is related to all fistulous burrowings. Ripens abscesses since it promotes suppuration." And in the skin section, the phrase every student remembers: "every little injury suppurates." Boger capitalises the same idea — "EVERY HURT FESTERS; stubborn suppuration; fistulæ; abscess; proud flesh; induration." Pus is offensive; ulcers are painfully sensitive, foul and spongy.
Expulsion of foreign bodies. Boericke: Silicea "promotes expulsion of foreign bodies from tissues"; Boger: "extrudes foreign bodies." This is the traditional indication for splinters, thorns, grit and retained fragments, and it is the clinical expression of the remedy's action on connective tissue.
Bone. "Diseases of bones, caries and necrosis," with Pott's disease, spinal caries and osteitis. Lippe records "inflammation and swelling of the bones and caries in any part," and "non-tuberculous curvation of the spine." The back is weak and "very susceptible to draughts."
Scar tissue and induration. Boericke: Silicea "can stimulate the organism to re-absorb fibrotic conditions and scar-tissue," with keloid growths, indurated tumours and scars that "suddenly become painful." Boger's phrase for the whole tendency is "slow, incomplete processes, then induration."
Sweat. Two locations, both characteristic. The head: "profuse sweat of head, offensive, and extends to neck" — Boger, "sweat; profuse; on upper parts; head." And the feet: "offensive sweat on feet, hands, and axillæ," which Boger sharpens to "FOOT-SWEAT; FOUL; itching; acrid, destroying shoes; suppressed." The suppressed foot sweat is a classical causation — complaints dating from the sudden disappearance of a habitual foot perspiration.
Rectum and stool. One of the most quoted symptoms in the materia medica, from Boericke: "stool comes down with difficulty; when partly expelled, recedes again." Boger's shorthand is "stools; receding." There is great straining, a rectum that stings and closes upon the stool, and constipation "always before and during menses." Fistula in ano and painful fissures with sphincter spasm belong here too.
Throat and glands. Periodical quinsy; "pricking as of a pin in tonsil"; swollen parotid and cervical glands, hard and cold. Lippe notes "painless swelling of the glands with troublesome itching" and "suppuration of the glands."
Mouth. "Sensation of a hair on tongue" — a small, odd, highly confirmatory symptom that Boger extends to "as of a hair on tongue, in throat." Abscess at the root of the teeth; gums sensitive to cold air.
Stomach. "Disgust for meat and warm food"; Boger's "averse to hot food" and, in infants, "averse to mother's milk; vomits it." Thirst is excessive.
Respiratory. Colds that fail to yield, with sputum "persistently muco-purulent and profuse"; slow recovery after pneumonia; "violent cough when lying down, with thick, yellow lumpy expectoration." Boericke records the memorable detail of expectorated "little granules like shot, which, when broken, smell very offensive."
Eyes. Styes, swelling of the lachrymal duct, perforating or sloughing corneal ulcer, and corneal opacity following keratitis — for which Boericke advises the 30th potency "for months."
Key Modalities
Worse from:
- Cold in every form — cold air, draughts, damp, bathing, washing
- Uncovering, especially the feet and head
- Checked or suppressed foot sweat
- New moon / change of moon — an unusual periodicity Boericke records explicitly
- Morning; night; lying down; lying on the left side
- During menses
- Noise, light, jarring the spine, nervous excitement
- Mental exertion; alcohol
Better from:
- Warmth in general, and wrapping the head up warmly in particular
- Summer, and wet or humid weather
- Pressure on the head
- Profuse urination
The head modality is worth isolating because it is so specific. A headache beginning in the occiput, spreading forward and settling over the eyes, relieved by wrapping the head warmly and by pressure, in a chilly patient, is Silicea until proven otherwise. Lippe's "daily headache beginning in the neck" describes the same pattern.
Keynote Symptoms
- Want of grit — yielding, faint-hearted, anticipating failure, yet obstinate
- Every little injury suppurates; stubborn abscesses, fistulae, slow healing
- Promotes expulsion of foreign bodies — splinters, thorns, grit
- Marked chilliness; lack of vital heat; hugs the fire; hates draughts
- Profuse offensive head sweat, extending to the neck
- Acrid, foul foot sweat that destroys shoes; complaints from its suppression
- The receding stool — partly expelled, then slips back
- Sensation of a hair on the tongue
- Pricking as of a pin in the tonsil
- White spots on the nails; crippled or ingrowing nails
- Headache from occiput to eyes, better wrapping the head warmly
- Aggravation at the new moon
- Parts lain on go to sleep
- Intolerance of alcohol; disgust for meat and warm food
Clinical Applications
Abscesses, boils and felons. The central indication. Silicea suits the stage where suppuration is established but will not resolve — the abscess that discharges thin, offensive pus and refuses to close, the whitlow, the recurrent boil. Boericke notes it "ripens abscesses," so it can also be used to bring a slow, cold, indolent swelling to a head.
Fistulae and sinuses. Fistula in ano, dental sinuses, fistulous ulcers of the breast, chronic discharging ears. Lippe lists "of marked usefulness in running ears and fistula lachrymalis" and "psoas abscess."
Retained foreign bodies. Splinters, thorns and other small foreign material that the tissue has walled off rather than expelled.
Failure to thrive in children. Large head, open fontanelles, distended abdomen, thin limbs, late walking, poor assimilation, sweaty head at night. Boericke's classical picture of the rachitic child.
Chronic constipation. The receding stool with sphincter spasm, straining, and aggravation before and during menses.
Recurrent tonsillitis and quinsy. Periodical, with the pin-prick sensation, in a chilly patient with swollen cervical glands.
Ill effects of vaccination. A traditional indication Boericke states directly, alongside Thuja — the two are complementary in his relationship list.
Corneal ulcers and opacities. With the specific instruction to use the 30th potency over a prolonged period.
Differential Diagnosis
Silicea vs. Hepar sulphuris. Both are chilly, oversensitive and suppurative, and Boericke notes Silicea follows Hepar well. Hepar belongs to the acutely painful stage — splinter-like pains, extreme sensitivity to touch, irritability bordering on violence. Silicea belongs to the chronic, indolent stage — less pain, more induration, a yielding rather than an angry patient.
Silicea vs. Calcarea carbonica. Both suit the scrofulous child with a large head, open fontanelles, head sweat and slow development, and Silicea follows Calcarea well. Calcarea is fat, flabby, fair and sluggish, with clammy sweat and cravings for eggs and indigestible things. Silicea is thin, fine and undernourished, with acrid foot sweat, suppuration and mental sharpness set against bodily weakness.
Silicea vs. Pulsatilla. Both are mild, yielding and easily moved, and Boericke lists them as complementary. Pulsatilla is warm-blooded, thirstless, changeable and better in the open air; Silicea is chilly, thirsty, fixed in its symptoms and worse from any draught. Consolation helps Pulsatilla; Silicea simply wants to be warm.
Silicea vs. Sulphur. Both are used in chronic, deep-acting prescribing with skin and suppurative involvement. Sulphur is hot-blooded, throws off heat, kicks off the covers and burns at the vertex and soles; Silicea is cold, wraps up, and hugs the fire. This thermal opposition alone usually settles the choice.
A relationship caution. Boericke states that Mercurius and Silicea do not follow each other well — worth remembering when planning a sequence of remedies in a chronic case.
Repertorisation Tips
These rubrics carry Silicea in high grade:
- Mind; TIMIDITY; bashful and Mind; IRRESOLUTION — the "want of grit" complex
- Mind; ANXIETY; anticipation, from — often with Gelsemium and Lycopodium
- Generalities; SUPPURATION; tendency to
- Generalities; WOUNDS; suppurating
- Rectum; CONSTIPATION; difficult stool; receding — a small and highly confirmatory rubric
- Perspiration; OFFENSIVE; foot sweat and Feet; PERSPIRATION; offensive, acrid
- Generalities; COLD; air; agg. and Generalities; DRAFT; agg.
- Head; PERSPIRATION; scalp, of
- Head; PAIN; wrapping up head; amel.
- Mouth; SENSATION; hair, of, on tongue
- Throat; PAIN; splinter, as from a
- Generalities; MOON; new moon; agg.
The productive combination pairs a mental rubric (bashful timidity, anticipatory anxiety) with the two physical generals that define the remedy — chilliness with aggravation from draughts, and the suppurative tendency. Add one of the small confirmatory rubrics, such as the receding stool or the hair on the tongue, and Silicea separates cleanly from Calcarea and Hepar. Our beginner's guide to repertorisation sets out the method in more detail.
Deepening Your Study
Silicea repays reading across authors, because each records something the others compress:
- Boericke supplies the pathology, the constitutional picture and the "want of grit" phrase, plus the practical cautions on potency and on phthisis
- Boger's Synoptic Key gives the fastest revision route; "EVERY HURT FESTERS" and "slow, incomplete processes, then induration" are the whole remedy in two lines
- Clarke's Dictionary holds the fullest compilation of proving and clinical symptoms, and is the source most often searched for by name
- Lippe's Keynotes preserves the causations — uncovering the feet and head, wine, suppressed foot sweat
- Kent's Lectures develop the mental state and the relationship between the yielding surface and the underlying obstinacy
You can read all of these side by side for any remedy through Similia's free digital materia medica. To place Silicea among its peers, see the guide to the essential polycrest remedies, or read how materia medica and repertory work together in case analysis.
