The work of Henry James is generally agreed to be split into three sections. In the first section he wrote works that mainly focused on the impact of the class between Europe, the older (and seen by many as being more corrupt) civilisation and America, the newer, younger and more innocent civilisation. His second stage is characterised by a shift towards an exclusively English focus, where he presented and explored the English character and developed his psychological study of his subjects. Critics remark that some of these texts verge on the unreadable. Finally, his "major phase," as it is known, came when he wrote his last three novels which are generally recognised as being his most successful: The Ambassadors, The Wings of the Dove and The Golden Bowl. The Turn of the Screw was written at the end of his second stage of writing, and fortunately is immensely readable and very gripping.
In particular, note the way that this story represents an in-depth psychological study of the governess, but also crucially is full of ambiguity, ensuring that readers ever since have remained doubtful abotu the precise fate of James. Note how the final words of this novella create this ambiguity:
I caught him, yes, I held him--it may be imagined with what a passion; but at the end of the minute I began to feel what it truly was that I held. We were alone with the quiet day, and his little heart, dispossessed, had stopped.
The question that every reader has been forced to confront is whether James died through terror at the final confrontation with Peter Quint or whether the governess strangled him with her "passion." This represents a much stronger focus on psychological concerns that are clearly the hallmark of James' second literary period.