337. The most refined humane intellect exerted to its utmost reach can only seize some imperfect glympses of the divine ideas, abstracted from all things corporeal, sensible, and imaginable. Therefore Pythagoras and Plato treated them in a mysterious manner, concealing rather than exposing them to vulgar eyes; so far were they from thinking, that those abstract things, altho' the most real, were the fittest to influence common minds, or become principles of knowledge, not to say duty and virtue, to the generality of mankind.
338. Aristotle and his followers have made a monstrous representation of the Platonic ideas; and some of Plato's own school have said very odd things concerning them. But if that philosopher himself was not read only, but studied also with care, and made his own interpreter, I believe the prejudice that now lies against him would soon wear off or be even converted into a high esteem for those exalted notions and fine hints, that sparkle and shine throughout his writings; which seem to contain not only the most valuable learning of Athens and Greece, but also a treasure of the most remote traditions and early science of the east.
George Berkeley, Siris. On Berkeley's conception of Platonic ideas, ideas aren't abstract in the sense of being 'abstract ideas', but in the sense of not being sensible. Ideas like beauty and goodness are instead active causes, intellectual beings that have more reality and stability than sensible things do. Although he doesn't explicitly say so -- the book is devoted to throwing out 'hints' rather than outright statements -- the point in context seems clearly that Berkeley takes Platonism to be true, or at least a likely speculation, insofar as the the Platonic Ideas can be regarded as God Himself.
But, of course, the question of Berkeley's Platonism has not gotten quite the study required to answer the complicated questions the subject raises.