The ultimate reason of things must lie in a necessary substance, in which the differentiation of the changes only exists eminently as in their source; and this is what we call God.
But in simple substances the influence of one monad over another is ideal only.
Nothing is in the intellect that was not first in the senses, except the intellect itself.
Music is the pleasure the human mind experiences from counting without being aware that it is counting.
I hold that the mark of a genuine idea is that its possibility can be proved, either a priori by conceiving its cause or reason, or a posteriori when experience teaches us that it is in fact in nature.
There is nothing in the understanding which has not come from the senses, except the understanding itself, or the one who understands.
There are also two kinds of truths: truth of reasoning and truths of fact. Truths of reasoning are necessary and their opposite is impossible; those of fact are contingent and their opposite is possible.
Indeed every monad must be different from every other. For there are never in nature two beings, which are precisely alike, and in which it is not possible to find some difference which is internal, or based on some intrinsic quality.
It is true that the more we see some connection in what happens to us, the more we are confirmed in the opinion we have about the reality of our appearances; and it is also true that the more we examine our appearances closely, the more we find them well-sequenced, as microscopes and other aids in making experiments have shown us.
I also take it as granted that every created thing, and consequently the created monad also, is subject to change, and indeed that this change is continual in each one.
The means of obtaining as much variety as possible, but with the greatest possible order...is the means of obtaining as much perfection as possible.
This is the best of all possible worlds.
The present is big with the future.
He who hasn't tasted bitter things hasn't earned sweet things. Nothing is necessitated whose opposite is possible.
It is unworthy of excellent men to lose hours like slaves in the labour of calculation which could safely be relegated to anyone else if machines were used.Gottfried Wilhelm Liebniz