Final answer:
The mixed metaphor used by Hemingway implies that life is too unpredictable, which is demonstrated through the unpredictable nature of the game and the lack of preparation for its strict rules and consequences.
Step-by-step explanation:
The mixed metaphor in Hemingway’s quote 'you have never had time to learn.
They threw you in and told you the rules and the first time they caught you off base they killed you' suggests that Henry feels life is too unpredictable.
By blending the contexts of learning, baseball (being off base), and the finality of death, Hemingway conveys a sense that life is a game with harsh consequences and a lack of preparation for its challenges.
This aligns with Hemingway's well-known narrative technique where underlying meanings are concealed beneath the surface, akin to his 'iceberg approach'.
Moreover, this metaphorical expression reflects the uncertainty and abrupt changes that characterize the life experiences of Hemingway's characters, often shaped by war and personal conflict, as seen in his works like 'A Farewell to Arms' and 'The Old Man and the Sea'.