Part 3: The origin and nature of the emotions

Most writers on the emotions and on human conduct seem to be treating rather of matters outside nature than of natural phenomena following nature's general laws.

The illustrious Descartes believed that the mind has absolute power over its actions.

For now, I will to revert to those, who would rather abuse or deride human emotions than understand them.


  1. An adequate cause is a cause through which its effect can be clearly and distinctly perceived.
    • An inadequate or partial cause is a cause through which, by itself, its effect cannot be understood.
  2. When anything happens within us or externally to us, we act and become our own adequate cause.
    • We become our own adequate cause (by the foregoing definition) when something happens within us or externally to us, which can only be clearly and distinctly understood through our nature.
    • On the other hand, we are only the partial cause for something that happens within us, or follows from our nature externally, which we are passive about.
  3. Emotions are:
    • the modifications of the body which increases or reduces the body's active power, aided or constrained, and
    • also the ideas of such modifications.
    • Note: If we can be the adequate cause of any of these modifications, I then call the emotion an activity.
      • Otherwise, I call it a passion or state wherein the mind is passive.


  1. The human body can be affected in many ways which increases or reduces its power of activity.
    • It can also be affected in other ways which do not change this power.
    • Note: This postulate or axiom rests on Postulate 1 and Lemmas 5 and 7, which is after 2.13.
  2. The human body can undergo many changes.
    • Nevertheless, it can retain:
      • the impressions or traces of objects (cf. 2. Post. 5) and
      • consequently, the same images of things (see note 2.17).
Proposition 1: Our mind is active in certain cases, and passive in certain cases. Proof: In every human mind, there are some adequate ideas, and some ideas that are fragmentary and confused (2. 40. note). Corollary: It follows that the mind is more or less liable to be acted upon, as it has inadequate ideas. Proposition 2: The body cannot determine the mind to think. Proof: God is the cause of all modes of thinking, by virtue of his being a thinking thing, and not by virtue of his being displayed under any other attribute (2.6).
  1. Everything cannot spring from the mind, which is a mode of thought because:
    • The motion a body must arise from another body, which has also been determined to a state of motion by a third body.
    • Absolutely everything which takes place in a body must spring from God, as he is regarded as affected by some mode of extension, and not by some mode of thought (2.6.)
  2. Therefore, the body cannot determine the mind, etc. Q.E.D.
Note: This is made clearer by what was said in the note to 2.7: that mind and body are one and the same thing.

They are conceived:

  1. Under the attribute of thought
  2. Under the attribute of extension

Thus, it follows that the order or concatenation of things is identical, whether nature be conceived under the one attribute or the other.

I do not think that men can be induced to consider the question calmly and fairly.

No one knows:

Thus, when men say that this or that physical action has its origin in the mind, which latter has dominion over the body, they:

But they will say that:

But I ask them whether experience does not also teach, that if the body be inactive the mind is simultaneously unfitted for thinking?

But it is impossible that solely from the laws of nature considered as extended substance, we should be able to deduce the causes of buildings, pictures, and things of that kind, which are produced only by human art.

As for the second objection, the world would be much happier if people were as fully able to keep silence as they are to speak.

However, unless such persons had proved by experience that we do many things which we repent of afterwards, and again that we often, when assailed by contrary emotions,

Experience teaches us that men believe themselves to be free, simply because:

The dictates of the mind are just another name for the appetites.

All these considerations clearly show that a mental decision and a bodily appetite, or determined state, are simultaneous, or rather are one and the same thing.

This will be more obvious in the sequel.

Are there two sorts of decisions in the mind:

  1. Illusive
  2. Free

We must admit that the mind's free decision is not distinguishable from the imagination or memory.

Proposition 3: The mind's activities arise solely from adequate ideas.

The mind's passive states depend solely on inadequate ideas.

Proof: The first element, which constitutes the essence of the mind, is nothing else but the idea of the actually existent body (2.11. and 2.13), which (2.15) is compounded of many other ideas, whereof some are adequate and some inadequate (2.29. Coroll., 2.38. Coroll.).

Note: Thus we see, that passive states are not attributed to the mind, except in so far as it contains something involving negation, or in so far as it is regarded as a part of nature, which cannot be clearly anythingd distinctly perceived through itself without other parts:

Proposition 4: Nothing can be destroyed, except by a cause external to itself.

Proof: This proposition is self-evident.

Proposition 5: Things are naturally contrary, that is, cannot exist in the same object, in so far as one is capable of destroying the other.

Proof: If they could agree together or co-exist in the same object, there would then be in the said object something which could destroy it; but this, by the foregoing proposition, is absurd, therefore things, etc. Q.E.D.

Proposition 6: Everything in itself endeavours to persist in its own being.

Proof: Individual things are modes whereby the attributes of God are expressed in a given determinate manner (1.25. Coroll.).

Proposition 7. The endeavour, wherewith everything endeavours to persist in its own being, is nothing else but the actual essence of the thing in question.

Proof: From the given essence of anything certain consequences necessarily follow (1.36), nor have things any power save such as necessarily follows from their nature as determined (1.29).

Proposition 8: The endeavour, whereby a thing endeavours to persist in its own being, involves no finite time, but an indefinite time.

Proof: If it involved a limited time, which should determine the duration of the thing, it would then follow solely from that power whereby the thing exists, that the thing could not exist beyond the limits of that time, but that it must be destroyed; but this (3.4) is absurd.

Proposition 9: The mind has clear, distinct, and confused ideas which consicously persist for an indefinite period

Proof: The essence of the mind is made up of adequate and inadequate ideas (3.3)

Note: This endeavour, when referred solely to the mind, is called will.

The only difference between appetite and desire is desire is generally applied to men being conscious of their appetite.

Proposition 10: An idea, which excludes the existence of our body, cannot be postulated in our mind, but is contrary thereto.

Proof: Whatsoever can destroy our body, cannot be postulated therein (3.5).

Next: Propositions 11-38