How did George Berkeley challenge Locke’s account of physical objects?

George Berkeley challenged John Locke’s account of physical objects by rejecting the existence of material substance and the distinction between primary and secondary qualities.123

While Locke argued that physical objects possess "primary qualities" (such as extension, figure, and motion) that exist independently in the world, and "secondary qualities" (such as color and taste) that are merely effects on the mind, Berkeley argued that this dualism is spurious. Berkeley contended that primary qualities are just as subjective as secondary ones; because all qualities are perceived through the senses, they are all "sensible ideas" that exist only within the mind.2314

Berkeley’s critique centered on his doctrine of esse est percipi ("to be is to be perceived"). He argued that because we only ever perceive ideas, it is contradictory to posit an imperceptible "material substrate" or "matter" underlying those ideas, as Locke had proposed. Instead, Berkeley concluded that physical objects are simply collections of sensible ideas. He maintained that these objects continue to exist when not perceived by humans because they are constantly perceived by the mind of God.243