Mike Jay writes:
How can opium be so ancient, and addiction so modern? The drug has not changed, nor has the human metabolism. In the earliest written records – Sumerian tablets and Egyptian papyri – it is already praised as a euphoric, a sedative and a supreme remedy against pain. Galen and his contemporaries added cautions about its dangers, but the most emphatic of these concerned overdose: the difference between an effective dose and a lethal one is uncomfortably small, and the tolerance that develops rapidly with regular use means that no standard dose can be stipulated. Compared to this urgent caveat, the need to increase dosage over time was little more than a footnote: for most classical authorities it merited less attention than the other universal side-effect of regular use, constipation.