A huge amount of stuff you do in any program is logic (branching), math (add, subtract, etc), and enumeration (various forms of looping). Algol/C does all these with built in language syntax. Smalltalk though, does not. It does these very elemental things, what might make up maybe 80% of a method body, with messages (or at least the facade there of). It couldn’t do logic and enumeration without closures. Objective C did not have theses so you still did that core 80% of stuff with old fashioned C.