We gain an early insight into Lennies problem when?

We see Lennie's mental challenges from the first time he appears in the novel. Lennie is 'a huge man, shapeless of face'. He stops and slurps from a stream like an animal

' ..with long gulps, snorting into the water like a horse.'

His childish amusement is evident as he makes ripples in the pool-

"Look, George. Look what I done."

He copies all of George's movements and follows his instructions. Lennie reveals his limitations quite quickly.