One day the world will look upon research upon animals as it now looks upon research on human beings.

Let not your rage or malice destroy a life.

Perspective is a most subtle discovery in mathematical studies, for by means of lines it causes to appear distant that which is near, and large that which is small.

It is the infinite alone that cannot be attained, for if it could it would become finite.

He who in reasoning cites authority is making use of his memory rather than of his intellect.

Every loss which we incur leaves behind it vexation in the memory, save the greatest loss of all, that is, death, which 89 annihilates the memory, together with life.

Wherever good fortune enters, envy lays siege to the place and attacks it; and when it departs, sorrow and repentance remain behind.

He only moves toward the perfection of his art whose criticism surpasses his achievement.

If we make mistakes in our first compositions and do not know them, we may not amend them.

Lying on a feather mattress or quilt will not bring you renown.