| 5685 | True ideas are images, such as of a man, a chimera, or God [Descartes] |
| 21807 | Ideas are powerful entities, which can produce further ideas [Spinoza, by Schmid] |
| 4830 | An 'idea' is a mental conception which is actively formed by the mind in thinking [Spinoza] |
| 4842 | Ideas are not images formed in the brain, but are the conceptions of thought [Spinoza] |
| 20311 | An idea involves affirmation or negation [Spinoza] |
| 6486 | Ideas are the objects of understanding when we think [Locke] |
| 15967 | The word 'idea' covers thinking best, for imaginings, concepts, and basic experiences [Locke] |
| 12496 | Complex ideas are all resolvable into simple ideas [Locke] |
| 12945 | Thoughts correspond to sensations, but ideas are independent of thoughts [Leibniz] |
| 12938 | An idea is an independent inner object, which expresses the qualities of things [Leibniz] |
| 19357 | The idea of green seems simple, but it must be compounded of the ideas of blue and yellow [Leibniz] |
| 12950 | We must distinguish images from exact defined ideas [Leibniz] |
| 19427 | True ideas represent what is possible; false ideas represent contradictions [Leibniz] |
| 19423 | By an 'idea' I mean not an actual thought, but the resources we can draw on to think [Leibniz] |
| 5374 | Berkeley probably used 'idea' to mean both the act of apprehension and the thing apprehended [Russell on Berkeley] |
| 23630 | Only philosophers treat ideas as objects [Reid] |
| 12615 | Mental representations are the old 'Ideas', but without images [Fodor] |
| 5636 | Cartesian 'ideas' confuse concepts and propositions [Scruton] |