Indeed in general I hold that there is nothing truer than happiness, and nothing happier and sweeter than truth.

The past is pregnant with the present.

It is worth noting that the notation facilitates discovery. This, in a most wonderful way, reduces the mind's labour.

It is a good thing to proceed in order and to establish propositions. This is the way to gain ground and to progress with certainty.

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

To love is to take delight in happiness of another, or, what amounts to the same thing, it is to account another's happiness as one's own.

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.