Some strains (typically those with a higher proportion of indica genes) are narcotic in their effects, tending to stupefy. Others (often the ones with more sativa genes) leave the mind clear and fluent and the body unimpaired. Some of the growers I met spoke in terms of “white-collar” and “blue-collar” pot. The strains I found personally sympathetic were stimulating and, evidently, conducive to mental speculation.