To be is to be perceived

Man is an Animal, formidable both from his Passions and his Reason; his Passions often urging him to great Evils, and his Reason furnishing Means to achieve them. To train this Animal, and make him amenable to Order; to inure him to a Sense of Justice and Virtue, to withhold him from ill Courses by Fear, and encourage him in his Duty by Hopes; in short, to fashion and model him for Society, hath been the Aim of civil and religious Institutions; and, in all Times, the Endeavour of good and wise Men. The aptest Method for attaining this End, hath been always judged a proper Education.

The method of Fluxions is the general key by help whereof the modern mathematicians unlock the secrets of Geometry, and consequently of Nature.

Doth the Reality of sensible things consist in being perceived? or, is it something distinct from their being perceived, and that bears no relation to the mind?

I might as well doubt of my own being, as of the being of those things I actually see and feel.

But, say you, surely there is nothing easier than for me to imagine trees, for instance, in a park [. . .] and nobody by to perceive them. [...] The objects of sense exist only when they are perceived; the trees therefore are in the garden [. . .] no longer than while there is somebody by to perceive them.

Truth is the cry of all, but the game of few.