As a Smalltalk dev for a couple of years, I feel my biggest moments of enlightenment were not with Smalltalk, but Scheme (i.e., Lisp) and (yes, not a popular opinion) Javascript (Prototype-based language that eschewed rigid class hierarchies).

I still love Smalltalk but it's elegance (message passing FTW) and purity set a bar too high for me, and it still fell afoul of the fact that class hierarchies create a syntax/behavior that require you to re-learn a lot every time you join a new project (too many companies/projects rewired basic class functionality).