Dr.Dudgeon in his Lectures and Practice of Homoeopathy says that following factors led Hahnemann to arrive at the concept of minimum dose.
a) Hahnemann observed that medicines exhibited greater strength when given in dilution than in dry state.
b) He observed the greater power of medicine when given in divided dose than given at once.
c) He observed the greater susceptibility of disease organism for the medicine having a specific homoeopathic relation to the affected parts.
d) Hahnemann observed an increasing power of medicine by a thorough admixture of vehicle by means of succusion
e) To avoid aggravation of disease when given in large doses.