This work can be regarded as an outline of behavior (human nature) from our greatest descriptive psychologist. In considering these matters we must keep in mind that philosophy is the descriptive psychology of higher order thought (DPHOT), which is another of the obvious facts that are totally overlooked –i.e., I have never seen it clearly stated anywhere. Sadly, Wittgenstein's brilliant exposition of behavior is still understood well by only a handful.
Much of the work is aimed at undermining the idea of introspection and private language via clever examples and of course there is a mountain of literature on this topic since but neither W nor anyone else ever makes it clear that the basic argument is trivial—if you don’t have a test that distinguishes between two words they cannot have a role in language and there cannot be any such test for private mental phenomena. In between he is describing how System 1 (the automatic functions of the brain) is described by intransitive uses of verbs such as seeing, remembering (i.e., they are Causally Self Reflexive) and differs from and blends into System 2- the deliberative linguistic system (e.g. p101, 161, 166 etc.). He spends much time showing that disposition words (S2) such as thinking, meaning, judging, interpreting, knowing, understanding, believing, intending, reading, calculating, recognizing, comparing, deciding, counting, imaging etc. are not mental states with a precise duration but that their use depends on their having a clear public outcome-i.e., being transitive verbs (i.e., having Conditions of Satisfaction, which is the phrase Searle invented decades later). They are abilities to act.
I suggest that with the perspective I propose, W is not obscure, difficult or irrelevant but scintillating, profound and crystal clear and that to miss him is to miss one of the greatest intellectual adventures possible.
Those wishing a comprehensive up to date framework for human behavior from the modern two systems view may consult my book ‘The Logical Structure of Philosophy, Psychology, Mind and Language in Ludwig Wittgenstein and John Searle’ 2nd ed (2019). Those interested in more of my writings may see ‘Talking Monkeys--Philosophy, Psychology, Science, Religion and Politics on a Doomed Planet--Articles and Reviews 2006-2019 3rd ed (2019), The Logical Structure of Human Behavior (2019), and Suicidal Utopian Delusions in the 21st Century 4th ed (2019)