poison kills poison

According to science we cannot create anything; we can simply change the form. The things which exist today are because something was already there. A drug, in its proving, can evoke in each case only what was already there, latent in the prover - even as disease brings out only weak points and therefore does not affect two patients in exactly the same way. It requires many provers, of different types and different defective resistances, to bring out the complete picture of a drug pathogenesis.
Dr M.L.Tyler describes the action-reaction as follows:-
Every agent that acts on vitality (i.e. every medicine) more or less deranges the vital force and causes, for a longer or shorter period, certain alterations in the health of the individual. This is termed primary action.
Although this primary action is a conjoint product of the medicinal and vital powers, it is principally due to the former.
To this primary action our vital force endeavours to apply energetic opposition; and this automatic, life-preserving reaction goes by the name of secondary action, or counteraction.
To this primary action our vital force endeavours to apply energetic opposition; and this automatic, life-preserving reaction goes by the name of secondary action, or counteraction.
During the primary action of artificial morbific agents (medicines) on our healthy bodies, the vital force, as well be seen by the following examples, seems to behave in a passive, or receptive manner, as if compelled to receive impressions from without, acting on it and perverting its health. Then it appears to rally and to develop (a) an exactly opposite condition, if such is possible, the countereffect, proportionate to its own energy and to the intensity of the primary action. Or (b) where there is no condition exactly the opposite of the primary action, the vital force appears to "indifferentiate" itself, and,putting forth its superior strength, it extinguishes the morbid changes, thereby restoring normal health. This is the after-effect, or curative effect.
A hand bathed in hot water is at first much warmer than the other; but, taken out and dried well, it will, after a while, grow colder than the other hand (after-effect or secondary action).
A person heated by violent excercise (primary action) is afterwards affected by chilliness and shivering (secondary action).
To one heated the previous day by drinking a lot of win (primary action), today every breath of air feels too cold (secondary action).
Excessive vivacity after strong coffee (primary action) entails sluggishness and drowsiness for a long time afterwards (reaction- secondary action)
if they are not removed for a short time by taking fresh supplies of coffee (palliative).
After the profound, stupefied sleep caused by opium (primary actkion), the following night will be all the more sleepless (reaction- secondary action).
After the constipation produced by opium (primary action) diarrhoea ensures (secondary action);
and after purgation with medicines that irritate the bowels, constipation for several days ensues (secondary action).
In a like manner it always happens, after the primary action of a medicine which, in large doses, produces a great change in the health of a healthy person, that its exact opposite, provided there is such a thing, is produced in the secondary action by our vital force.
As following the action of minute homoeopathic doses in health,
obvious secondary effects are perceived very little.
For though such minute doses, closely observed, will be found to produce a perceptible primary effect, yet the living organism sets up only such countereffect as is absolutely required to re-established normal conditions.