A man approaches a woman who is playing with a puppy in her front yard. He asks to buy the puppy. She refuses.
Later that night he takes the puppy from the back yard and leaves an envelope with $1,200 in it, more than the woman paid for the puppy. Has he committed an offence? If so, why?
Yes, he is guilty of theft. He has treated the puppy as his own. This is an appropriation. Despite the fact that he was willing to pay he had no legal right to the dog.