I've been puzzled with Albrecht Dürer's work for a while now.

I would assume that most people who have taken interest in landsknechte are familiar with the brustfleck i.e. the piece of fabric to cover the chest as doublets were being worn open (The earliest example I've found on the net claimed to be dated 1484, see the attachment)
This develops into the well known U shaped opening and the brustfleck underneath. Then out of nowhere I stumble into these:
Why would anyone need a brustfleck at the back? besides, the second image shows the seam following the shapes of the wearers back so accurately I doubt it would depict a separate piece.

Until yesterday I had no clue about the origin of these. Then it struck me that the 15thC Italian/Southern european doublet had a U shaped neckline
I just scuffled thorugh some other works by Dürer and Diebold Schilling, and now the connection seems obvious:
Another case of renaissance-fashion-transition-oriented-mind-blown-ness. However, there's still some puzzling stuff I hope to hear more educated people's opinions about. Dürer has a few pictures with Brustflecks that have buttoning in the front:

It is often stated (perhaps overly simplifying the historical reality?) that in mid-late 15thC it started to be fashionable in northern europe to have the doublet close at the waist, and have a V-shaped opening across the chest. The attached picture could show a logical development to cover that opening, as the opening is quite wide at the top and no longer follows the neckline. I should probably find out where this picture originated... The U shaped collar/backseam is a southern european/swiss thing. Simultaneosly with the U-backseams becoming extreme, there are similar seams at the front, with buttons to close the garment. If the U shape was just a fashionable thing, the covering of the northern european V-opening might have nothing to do with it. Perhaps it's a pointless "egg or hen" discussion, these weren't cultures divided by any clear boundary so it's not clear what influenced the other first.

Also, this guy has some very funky seams/cords? starting from his overgrown U collar

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1484 brustfleck.JPG