Enlarge (credit: Olena Ruban via Getty Images) The 1960s was a big decade for cannabis: Images of flower power, the summer of love and Woodstock wouldn’t be complete without a joint hanging from someone’s mouth. Yet in the early ’60s, scientists knew surprisingly little about the plant. When Raphael Mechoulam, then a young chemist in his 30s at Israel’s Weizmann Institute of Science, went looking for interesting natural products to investigate, he saw an enticing gap in knowledge about the hippie weed: The chemical structure of its active ingredients hadn’t been worked out. Mechoulam set to work. The first hurdle was simply getting hold of some cannabis, given that it was illegal.