“In sensation, properly so called, I can distinguish two things, the mind or sentient being, and the sensation. Whether the last is to be called a feeling or an operation, I dispute not; but it has no object distinct from the sensation itself. If in sensation there be a third thing, called an idea. I know not what it is.
“In perception, in remembrance, and in conception, or imagination, I distinguish three things, the mind that operates, the operation of the mind, and the object of that operation. That the object is perceived is one thing, and the perception of that object is another, I am as certain as I can be of any thing. The same may be said of conception, of remembrance, of love and hatred, of desire and aversion. In all of these, the act of the mind about its object is one thing, the object is another thing. There must be an object, real or imaginary, distinct from the operation of the mind about it. Now if in these operations the idea be a fourth thing different from the three I have mentioned, I know not what it is, nor have been able to learn from all that has been written about ideas. And if the doctrine of Philosophers about ideas confounds any two of these thins which I have mentioned as distinct; if, for example, it confounds the object perceived with the perception of that object, and represents them as one and the same thing, such a doctrine is altogether repugnant to all that I am able to discover of the operations of my own mind; and it is repugnant to the common sense of mankind, expressed in the structure of all languages.” (EIP, 2.11, p.161).
“[I]t seems very hard, or rather, impossible, to understand what is meant by an object of thought that is not an immediate object of thought. A body in motion may move another that was at rest, by the medium of a third body that is interposed. This is easily understood; but we are unable to conceive any medium interposed between a mind and the thought of that mind; and to think of any object by a medium seems to be words without any meaning.” (EIP 2.9, p. 134, 17-23).
“Conceiving as well as projecting or resolving, are what the schoolmen call immanent acts of the mind, which produce nothing beyond themselves. But painting is a transitive act, which produces an effect distinct from the operation, and this effect is a picture. Let this therefore be always remembered, that what is commonly called the image of thing in the mind, is no more than the act or operation of the mind in conceiving it.” (EIP, 4.I, p. 300)
“There is a sense in which a thing may be said to be perceived by a medium. Thus any kind of sign may be said to be the medium by which I perceive or understand the thing signified. The sign, by custom, or compact, or perhaps by nature, introduces the thought of the thing signified. But here the thing signified, when it is introduced to the thought, is an object of thought no less immediate than the sign was before: And there are here two objects of thought, one succeeding another, which we have shown is not the case with respect to an idea, and the object it represents” (EIP 2.9, p. 134, 24-31).
“Whether, according to the opinion of Philosophers, we perceive the images or ideas only, and infer the existence and qualities of the external object from what we perceive in the image? Or, whether we really perceive the external object as well as its image?” (EIP 2.7, 105, 28-32)
A third class of natural signs comprehends those which, though we never before had any notion or conception of the things signified, do suggest it, or conjure it up, as it were, by a natural kind of magic, and at once give us a conception, and create a belief of it. (IHM 5.3 p. 59–60)
I shall call an indicative sign any sign whose significant is of necessity unavailable to perception, and which serves as an indication of that significate. I depart from the Hellenistic tradition in leaving open the question of necessary connection. A reminiscent sign is one whose presence conveys the mind by a causal process to something else which has been experienced in conjunction with that sign. (Ott, Locke’s Theory of Language, p. 19)
“The argument which has probably done the most to produce a belief in ‘contents’ as opposed to objects is the last of those adduced by Meinong, namely that there must be some difference between a presentation of one object and a presentation of another, and this difference is not to be found in the ‘act’ of presentation. At first sight, it seems obvious that my mind is in different ‘states’ when I am thinking of one thing and when I am thinking of another. But in fact the difference of the object supplies all the difference required.” (Russell, Theory of Knowledge, 1984, p. 43)