A jacket can be neither thick nor thin, sturdy nor flimsy. It must be able to roll up into a neck pillow at any given moment or be draped over your legs and chest as an impromptu blanket.
Clockwise:
Urbancode, $160 ;
Uniqlo, $60 ;
Topshop, $395 ;
Helmut Lang, $395 ;
Petit Bateau, $236