Definitions

1. “Thought” includes all that is in us and of which we are immediately conscious.

Thus all operations of the will, intellect, imagination, and senses are thoughts.

But I have added ‘immediately’ so as to exclude those things that are their consequences. For example, voluntary motion has thought for its starting point, but in itself it is still not thought.

2. “Idea” is the specific form of a thought, through the immediate perception of which I am conscious of that same thought.

So whenever I say something that I understand, there is in me the idea of what is meant by those words.

‘Ideas’ are not images depicted in the fantasy.

Ideas are those that communicate their form to the mind itself.

3. The “objective reality of an idea” is the being of that which is presented through the idea

In the same way one can speak of ‘objective perfection’ or ‘objective art’, etc.

Whatever we perceive as being in the objects of ideas is objectively in the ideas themselves.

4. The “objects of ideas” are what we perceive them to be in themselves.

The cause contains eminently the perfections of its effect. This means that the cause contains the perfections of the effect with a higher degree of excellence than does the effect itself. See also Axiom 8.

5. “Substance” is everything in which there is something that we perceive as immediately inhering in a subject, or through which there exists something that we perceive (i.e., some property, quality or attribute whose real idea is in us).

Substance is a thing in which there exists formally that something which we perceive (i.e., that something which is objectively in one of our ideas).

6. Mind is substance in which thought immediately inheres.

I here speak of ‘Mind’ rather than ‘Soul’ (anima) because the word ‘soul’ is equivocal, and is often used to mean a corporeal thing.

7. Substance that is the immediate subject of extension and of accidents that presuppose extension, such as figure, position, and local motion, is called Body.

Whether what is called Mind and what is called Body is one and the same substance, or two different substances, is something to be enquired into later.

8. Substance that we understand through itself to be supremely perfect, and in which we conceive nothing at all that involves any defect or limitation of perfection, is called God.

9. When we say that something is contained in the nature or conception of some thing, that is the same as saying that it is true of that thing or can be truly affirmed of it.*

10. Two substances are said to be distinct in reality when each one can exist without the other.

We have here omitted the Postulates of Descartes because in what follows we do not draw any conclusions from them. But we earnestly ask readers to read them through and to think them over carefully.*