They changed like that.

We used to catch them and put them up in the corral, and they developed great cunning.

They would pretend to eat their oats like the other horses, but we knew they were always scheming to get back at the loco.
It seems that a man is meant to live only one life in this world.

When he tries to live a second, he develops another nature.

I feel as if a second man had been grafted into me.