George Berkeley was an Irish philosopher and Anglican bishop of Cloyne. While still young, he proposed a surprising thesis: material objects do not exist outside the mind, because to be is to be perceived. He also tried to found a college in Bermuda and spent a few years in North America.
Core ideas
To be is to be perceived: things exist only while they are perceived
There is no matter that exists independently of any mind
God perceives everything continuously and guarantees the stability of the world
The tradition: Empiricist idealist
An empiricist idealist starts from the experience of the senses, like the empiricists, but concludes that only minds and ideas exist. Berkeley is the main name of this position.