I'd always had a sneaking suspicious that we could mark the start of modernism by the date that we've held in the US as a constant for copyright protection for nearly a century now, c1924, iirc. Anything earlier was a product of a sort of naive, pre-collectively conscious state. Anything afterwards was developed within a culture that understood and desired to exploit and appropriate the worth of the creations or artifacts.

Why, then, did it take me so long to realize that 1924 marks exactly the period when psychotherapy and psychiatry went from cultural unknown to cultural given? The mark of the moment when US society became collectively conscious (whether it realized it or not, ironically enough) was exactly when psychiatry ontologically created the consciousness itself. Heck, if you believe wikipedia, Freud's "The Ego and the Id" was written/pubbed in 1923.

Coincidence, synchronicity, or conspiracy? Yes. ;^)