The sap of this, says De Candolle, would be poisonous if taken in large quantities, but in small doses merely induces hallucination. Opium and hashish, a preparation of the hemp plant, have been in general use among Eastern peoples, as a means of producing ecstasy from remote antiquity. Opium, it is well known, produces an extraordinary state of exaltation, intensifying the sense of one's personality, and inducing a pleasurable consciousness of mental strength and clarity. Under its influence, as De Quincey said, time lengthens to infinity and space swells to immensity.[26] Belladonna, a drug much used by medieval witches and sorcerers, has also had its vogue for purely religious purposes. With the Greeks the laurel was sacred to Æsculapius. Those who wished to ask counsel of the god appeared before the altar crowned with laurel and chewing its leaves. Before prophesying, the Greek priestesses drank a preparation of laurel water. This contains, although it was, of course, unknown to them, two toxic substances--prussic acid and the volatile oil of laurel. The first would induce convulsions, the second, hallucinatory visions. The two combined were calculated to produce with both subject and observer a profound impression of spiritual illumination and possession. It is unnecessary to multiply examples of the action of various drugs or herbs on the nervous system, or to cite the people who use them. Enough has been said to indicate how widespread is the practice, and the consequences are not hard to foresee. A very moderate development of intelligence would enable men to associate certain consequences with the use of particular drugs, but a very considerable amount of knowledge would be required to explain why these consequences were produced. In a social environment saturated with superstition the explanation lies ready to hand, and is accepted without question. A people that sees spiritual agency in all the familiar phenomena of nature are certainly not less likely to trace its influence in the mysterious and unaccountable effects of narcotics and stimulants. And each repeated experiment provides additional proof. Man thus not only believes himself to be surrounded by a spiritual world; he is actually able to enter into communication with it by methods that are defined in the clearest possible manner. Every repetition strengthens the delusion and even when the delusion, as such, is exploded, the temper of mind induced by it persists.