The Tree of Philosophy

All Philosophy is like a tree.

• Metaphysics is the root
• Physics the trunk
• All the other sciences are the branches that grow out of this trunk.

There are 3 principal sciences:

1. Medicine
2. Mechanics
3. Ethics

The science of Morals is the highest and most perfect. Presupposing an entire knowledge of the other sciences, it is the last degree of wisdom.

We gather fruit from the extremities of the branches of trees, not from the roots or the trunks.

Likewise, the principal utility of philosophy depends on the separate uses of its parts, which we can only learn at the end.

I am ignorant of almost all these. But my zeal in endeavouring to be of service to the public, was the reason why I published 10-12 years ago, Essays on the doctrines I thought I had acquired.

The first part of these Essays was a “Discourse on the Method of rightly conducting the Reason, and seeking Truth in the Sciences”.

It summarizes the principal rules of logic, and also of an imperfect ethic, which a person may follow provisionally so long as he does not know any better.

The other parts were 3 treatises:

1. Dioptrics

This shows that we might proceed far enough in philosophy as to arrive, by its means, at the knowledge of the arts that are useful to life, because the invention of the telescope, of which I there gave an explanation, is one of the most difficult that has ever been made.

2. Meteors

This shows the difference that subsists between the philosophy I cultivate and that taught in the schools, in which the same matters are usually discussed.

3. Geometry

I professed to demonstrate that I had discovered many things that were before unknown, and thus afford ground for believing that we may still discover many others, with the view of thus stimulating all to the investigation of truth.

Since that time, I had anticipated the difficulty which many would experience in apprehending the foundations of the Metaphysics.

This is why I wrote the small book of Meditations. It was enlarged with the Objections which several very learned persons sent to me about it, as well as my Replies.

At length, after it appeared to me that those preceding treatises had sufficiently prepared the minds of my readers for the Principles of Philosophy, I also published it.

I have divided this work into 4 parts:

1. The principles of human knowledge.

It may be called the First Philosophy, or Metaphysics.

This requires the reading of the book of Meditations beforehand.

The other 3 parts contain all that is most general in Physics

2. The explanation of the first laws or principles of nature.

This is how the heavens, fixed stars, planets, comets, and the whole universe, were composed.

3. The explanation of the nature of this earth, air, water, fire, and magnet

These are the bodies we most commonly find everywhere around the earth.

4. The explanation of all the qualities we observe in these bodies

Examples are light, heat, gravity, and the like.

In this way, I have made an orderly explanation of the whole of philosophy.

In the work’s conclusion, I also explain the nature of more particular bodies that are on the earth:

• minerals
• plants
• animals
• especially man

Finally, I treat thereafter Medicine, Ethics, and Mechanics.

I did this to give to the world a complete body of philosophy.

I am not yet so old. I still trust my strength. But I do not have the resources to make all the experiments I require to verify my reasonings.

I need the public’s help to fund those experiments, yet I have no ground to expect this aid.

I just content myself with studying for my own instruction. Posterity will excuse me if I fail to labour for those experiments.

What fruits may be gathered from my Principles?

1. The mental satisfaction from finding in the work many truths before unknown.

Frequently, truth does not so greatly affect our imagination as falsity and fiction. This is because truth is less wonderful and is more simple. Yet, the gratification it affords is always more durable and solid.

2. We will become gradually used to judging better all the things we come in contact with.

Thus, we are made wiser.

3. The resolution of all disputes

This is because the truths which my Principles contain are highly clear and certain. The resolution of disputes will dispose men’s minds to gentleness and concord.

This is the opposite of the effect of the controversies of the schools which now harass the world.

4. The discovery of many truths which I myself have not unfolded.

Thus, by passing by degrees from one truth to another, people will acquire in time a perfect knowledge of the whole of philosophy.

All the arts are rude and imperfect in their beginnings. Yet they are gradually perfected by practice, from their containing at first something true, and whose effect experience evinces.

Likewise, my philosophy has true principles which we follow to meet sometimes with other truths.

The best way to prove the falsity of Aristotle’s philosophy is to say that men have made no progress in knowledge throught it during the many ages that they studied it.

Fake Followers

Some men are so used to doing so little circumspection in their activities. They are unable to erect a firm superstructure even on the most solid foundations. Yet they are the readiest to write books. They would in a short time:

• mar all that I have done
• introduce uncertainty and doubt into my manner of philosophizing even if I have carefully endeavoured to banish them

Not long ago, one of my followers last year published a book “Fundamental Physics” based on my writings. He copied my writings badly, and changed the order, and denied certain metaphysical truths which all Physics should be based on.

[Footnote: Regius; see La Vie de M. Descartes, reduite en abrege (Baillet). Liv. vii., chap. vii.—T.]

I wholly disavow his work.

I ask readers:

• not to attribute to me any opinion unless they find it expressly stated in my own writings
• to receive no opinion as true, whether in my writings or elsewhere, unless they see that it is very clearly deduced from true principles.

Many ages may elapse where all the truths deducible from these principles are evolved out of them. This is because:

• more of the truths that remain to be discovered depend on experiments that never occur by chance
  • These experiments need careful investigation by men of the highest intelligence
• the same persons who have the sagacity to correctly use experiments, will also possess the means of conduciting them
• the majority of the best minds have formed so low an estimate of philosophy in general, that they cannot apply themselves to the search for truth

My highest wish is for posterity to behold the happy issue of it, etc.