The first hundred pages of William Barrett's The Illusion of Technique provide a very useful background / introduction to Wittgenstein's intellectual culture & to the transition from the logical atomism of the Tractatus to the natural language philosophy of the Investigations. It is surprising that Barrett's book, published in 1967, does not find its way into the Bibliography of Ray Monk's biography. I would call Barrett an Existentialist, but his own philosophical point of view remains in the background, a framework, as he elucidates Wittgenstein. Briefly, Barrett sees the Tractatus as leading to a point of intellectual sterility, though it was a point to which W was bound to travel, beginning with the Principia. The error--the dead end--turns out to be taking mathematical logic as the structure of the world & of human language, rather than as the specialized tool that it is. Barrett argues that it is the last few pages of the Tractatus, where W claims that he is kicking away the ladder of logic, that the enduring value of the work is to be found.

Those masterful images because complete
Grew in pure mind, but out of what began?
A mound of refuse or the sweepings of a street,
Old kettles, old bottles, and a broken can,
Old iron, old bones, old rags, that raving slut
Who keeps the till. Now that my ladder's gone,
I must lie down where all the ladders start
In the foul rag and bone shop of the heart.
[Yeats, "The Circus Animals Desertion"]