Somehow within the framework of our own particular folklore, the three Princes of Serendip are presented as practitioners of fortuitous misdirection. They have become the fellows who set out to look for a new refrigerant and wound up making a fortune from a new rocket propellant after one of them blew up his house, a consequence of lighting a candle when he neglected to pay for the electricity.
But this is only folklore. In the true tale they were masters of keen observation as well as of deductive reasoning (a horse passed this way at full gallop— presumably carrying a double burden; the depth, angle and periodicity of the hoofprints, and the dried spittle on the wayside foliage told us).
Thus has it ever been with those who first discover the adverse reaction to a therapeutic agent. The keen observation of the aberrant pattern—the canted, deepened hoofprint or the recrudescent