Lennie Small's state of mind, heading into the closing chapter of John Steinbeck's Of Mice and Men, is quite different from his state of mind at the opening of the novella. When coming to the water's edge in the opening of the text, Lennie throws himself down, without any caution at all, and begins gulping the water down "like a horse."
In the closing chapter, Lenny's actions are very different. Lennie is in no hurry to drink. Instead, he comes "quietly" to the edge of the water. When drinking, he does not gulp down the water. Lennie barely touches his mouth to the water's surface. He also jumps at the sound of a bird running over some leaves.
Therefore, Lennie's state of mind is confused. Not only is he not acting like himself, he is picturing large rabbits and his deceased aunt. His mind is not all there. He knows what he did was wrong (killing Curley's wife). He knows enough to go and hide (like the plans he made with George). This said, Lennie begins talking to people who, and animals that, are not there. This speaks to his confused state of mind.