Common sense says that chairs and tables exist independently of whether anyone happens to perceive them or not.
When I see a colour or hear a sound, I am aware of something, and not of nothing.
In Psychology we deal with minds and their processes, and leave out of account as far as possible the objects that we get to know by means of them.
Our analysis of truth and falsehood, or of the nature of judgment, is not very likely to be influenced by our hopes and fears.
In all the sciences except Psychology we deal with objects and their changes, and leave out of account as far as possible the mind which observes them.