Ainsi on peut dire que non seulement l'âme, miroir d'un univers indestructible, est indestructible, mais encore l'animal même, quoique sa machine pér… - Gottfried Wilhelm Leibniz

To the possible objection that thus the world would of necessity have long ago turned into a paradise, it is easy to reply: Many substances already may have attained great perfection; yet, the continuum being infinitely divisible, there will always remain in the unfathomable depth of the universe some somnolent elements which are still to be awakened, developed, and improved - in a word, promoted to higher culture. This is why the end of progress can never be attained.

Moreover, it must be confessed that perception and that which depends upon it are inexplicable on mechanical grounds, that is to say, by means of figures and motions. And supposing there were a machine, so constructed as to think, feel, and have perception, it might be conceived as increased in size, while keeping the same proportions, so that one might go into it as into a mill. That being so, we should, on examining its interior, find only parts which work one upon another, and never anything by which to explain a perception. Thus it is in a simple substance, and not in a compound or in a machine, that perception must be sought for.

He who understands Archimedes and Apollonius will admire less the achievements of the foremost men of later times.