It is our duty, my young friends, to resist old age.

Any man is liable to err, only a fool persists in error.

O wretched man, wretched not just because of what you are, but also because you do not know how wretched you are!

The hours pass and the days and the months and the years, and the past time never returns.

I criticize by creation - not by finding fault.

All pain is either severe or slight, if slight, it is easily endured; if severe, it will without doubt be brief.

When I consider the wonderful activity of the mind, so great a memory of what is past, and such a capacity of penetrating into the future: when I behold such a number of arts and sciences, and such a multitude of discoveries hence arising,--I believe and am firmly persuaded that a nature which contains so many things within itself cannot be mortal.