With the benefit of hindsight, we can also identify in Ludlow’s account a number of other features consistent with present knowledge, but which even scientists of his day could not possibly have known. For example, the initial change in tolerance, the continuum between euphoria and hallucinations, the differentiation between the hallucinatory process and the affective reactions to it, the relation between spontaneous and drug-induced perceptual changes, the similarity between the effects of cannabis and those of other hallucinogens, the attempts at drug substitution therapy (opium, tobacco), and the role of psychotherapy and abreactive writing, are all in keeping with contemporary thought. These points permit the modern reader to feel even greater confidence in the extraordinary accuracy and perceptiveness of Ludlow’s record.