A traditional
English language idiom. This phrase personifies
optimism: the belief that all things are possible and that
opportunity is limitless.
The phrase is often used as an answer to a general question on someone's outlook- their opinion on how things are going to work out on a particular endeavor or experience:
"How do you think that Alaskan oil drilling is going? "
"The sky's the limit!"
See also: rose colored glasses.