why homeopathic remedies have no molecule left of the original ingredient:
"Actually, the laws of chemistry state that there is a limit to the dilution that can be made without losing the original substance altogether. This limit, which is related to Avogadro's number, corresponds to homeopathic potencies of 12C or 24X (1 part in 1024). Hahnemann himself realized that there is virtually no chance that even one molecule of original substance would remain after extreme dilutions. But he believed that the vigorous shaking or pulverizing with each step of dilution leaves behind a "spirit-like" essence—"no longer perceptible to the senses"—which cures by reviving the body's "vital force." Modern proponents assert that even when the last molecule is gone, a "memory" of the substance is retained. This notion is unsubstantiated. Moreover, if it were true, every substance encountered by a molecule of water might imprint an "essence" that could exert powerful (and unpredictable) medicinal effects when ingested by a person.'