Theologian: But what is to love? Philosopher: To be delighted by the happiness of another.

Music is a hidden arithmetic exercise of the soul, which does not know that it is counting.

I have said more than once, that I hold space to be something purely relative, as time; an order of coexistences, as time is an order of successions.

Although the whole of this life were said to be nothing but a dream and the physical world nothing but a phantasm, I should call this dream or phantasm real enough, if, using reason well, we were never deceived by it.

This miracle of analysis, this marvel of the world of ideas, an almost amphibian object between Being and Non-being that we call the imaginary number.

We never have a full demonstration, although there is always an underlying reason for the truth, even if it is only perfectly understood by God, who alone penetrated the infinite series in one stroke of the mind.

The love of God consists in an ardent desire to procure the general welfare, and reason teaches me that there is nothing which contributes more to the general welfare of mankind than the perfection of reason.

And as every present state of a simple substance is naturally a consequence of its preceding state, so its present is pregnant with its future.

There are two kinds of truths: those of reasoning and those of fact. The truths of reasoning are necessary and their opposite is impossible; the truths of fact are contingent and their opposites are possible.

Now, as there is an infinity of possible universes in the Ideas of God, and as only one of them can exist, there must be a sufficient reason for God's choice, which determines him toward one rather than another. And this reason can be found only in the fitness, or the degrees of perfection, that these worlds contain, since each possible thing has the right to claim existence in proportion to the perfection it involves.

Thus there is nothing waste, nothing dead in the universe; no chaos, no confusions, save in appearence. We might compare this to the appearence of a pond in the distance, where we can see the confused movement and swarming of the fish, without distinguishing the fish themselves.Thus we are that each living body has a dominante entelechy, which in case of an animal is the soul, but the members of this living body are full of other living things, plants and animals, of which each has in turn ita dominant entelechy or soul.

There are two famous labyrinths where our reason very often goes astray. One concerns the great question of the free and the necessary, above all in the production and the origin of Evil. The other consists in the discussion of continuity, and of the indivisibles which appear to be the elements thereof, and where the consideration of the infinite must enter in.

My philosophical views approach somewhat closely those of the late Countess of Conway, and hold a middle position between Plato and Democritus, because I hold that all things take place mechanically as Democritus and Descartes contend against the views of Henry More and his followers, and hold too, nevertheless, that everything takes place according to a living principle and according to final causes - all things are full of life and consciousness, contrary to the views of the Atomists.

Only geometry can hand us the thread [which will lead us through] the labyrinth of the continuum's composition, the maximum and the minimum, the infinitesimal and the infinite; and no one will arrive at a truly solid metaphysic except he who has passed through this [labyrinth].

To love is to be delighted by the happiness of someone, or to experience pleasure upon the happiness of another. I define this as true love.

Everything that is possible demands to exist.

Every substance is as a world apart, independent of everything else except God.

As regards the objection that possibles are independent of the decrees of God I grant it of actual decrees (although the Cartesians do not at all agree to this), but I maintain that the possible individual concepts involve certain possible free decrees; for example, if this world was only possible, the individual concept of a particular body in this world would involve certain movements as possible, it would also involve the laws of motion, which are the free decrees of God; but these, also, only as possibilities. Because, as there are an infinity of possible worlds, there are also an infinity of laws, certain ones appropriate to one; others, to another, and each possible individual of any world involves in its concept the laws of its world.

TO LOVE is to find pleasure in the happiness of others. Thus the habit of loving someone is nothing other than BENEVOLENCE by which we want the good of others, not for the profit that we gain from it, but because it is agreeable to us in itself. CHARITY is a general benevolence. And JUSTICE is charity in accordance with wisdom. ... so that one does not do harm to someone without necessity, and that one does as much good as one can, but especially where it is best employed.

I am convinced that the unwritten knowledge scattered among men of different callings surpasses in quantity and in importance anything we find in books, and that the greater part of our wealth has yet to be recorded.

Even in the games of children there are things to interest the greatest mathematician.

The consequences of beliefs that go against the providence of a perfectly good, wise, and just God, or against that immortality of souls which lays them open to the operations of justice.... I even find that somewhat similar opinions, by stealing gradually into the minds of men of high station who rule the rest and on whom affairs depend, and by slithering into fashionable books, are inclining everything toward the universal revolution with which Europe is threatened, and are completing the destruction of what still remains in the world of the generous Greeks and Romans who placed love of country and of the public good, and the welfare of future generations before fortune and even before life.

I have seen something of the project of M. de St. Pierre, for maintaining a perpetual peace in Europe. I am reminded of a device in a cemetery, with the words: Pax perpetua; for the dead do not fight any longer: but the living are of another humor; and the most powerful do not respect tribunals at all. Letter 11 to Grimarest: Passages Concerning the Abbe de St. Pierre's 'Project for Perpetual Peace' (June 1712).

Thus it may be said that not only the soul, the mirror of an indestructible universe, is indestructible, but also the animal itself, though its mechanism may often perish in part and take off or put on an organic slough.