So wrote Dutch pharmacologist D.K. de Jongh as recently as 1964. For him and others, the cell receptor was something of an enigma. Not least, there was the problem of understanding how cells seemed to boast receptors for manmade chemical substances synthesized in the laboratory. For German professor of pharmacology Klaus Söhring speaking at a colloquium in Hamburg in the early 1950s, this conundrum was so great that it all but ruled out the existence of such specific receptors. After all, he argued, how could God, the Creator, have known which different kinds of pharmaceutical substances would be developed by mankind [2].