Of all the millions of words that have been written and spoken in the past five years on the subject of drug abuse, only four have undisputed validity. The words are: we do not know.

We can recognize trends; we can make estimates that appear to be developing some sophistication. But, on the basis of current information and methods by which the information is secured, we can only conclude that we are trying to deal with a condition, the limits of which we do not know.