Vincent Marinaro, 1950
Modern Dry Fly Code was first published in 1950 and it remains a popular work, having been reprinted at least twice. The Code attracted attention right from the start because there was more in it about terrestrials than there was about mayflies and also because the author focused attention on small imitations to an extent that had never been encouraged before. Marinaro was a brave man for doing it and for some time he stood out as a lone voice in the wilderness; he was challenged, for example, for suggesting that size 14 was the largest hook needed for a dry fly imitation (this was in the days before hooks were available in sizes below 20s). In retrospect, Marinaro probably kicked off a fashion for tiny patterns that went just a little too far before it corrected itself, but his basic point was well made.
Marinaro's other big idea was that the bodies of dry patterns held little attraction for fish and that only the wing needed to be imitated, which led him to design his 'thorax' patterns, which featured a unique method of tying hackle point wings at the mid-point of the hook, the whole fly being supported by a hackle wound in a 'X' configuration around it. You can see where he got the idea - after all, real flies do float on their toes, not their bellies - but in practice 'thorax' patterns sink into the film just like anything conventional dressings, which explains why you don't see them nowadays.
Marinaro's dressings were based on his historical knowledge - he quoted Ward, Dunne and Harding among others - and also on his own patient and acute observations. These reached fulfillment in his other work, In the Ring of the Rise, which featured some extraordinary photographic sequences of fish and flies. I can hardly recommend his books more highly - few writers have such a capacity for making the reader think.