Mankind? That is an abstraction. There have always been and always will be only individuals.

There are but few who have ideas and are, at the same time, capable of action. Ideas enlarge but stymie, action enlivens but confines.

I was oppressed with the sensations I then felt; I sunk under the weight of them.

Every bird has its decoy, and every man is led and misled in his own peculiar way.

It is much easier to meet with error than to find truth; error is on the surface, and can be more easily met with; truth is hid in great depths, the way to seek does not appear to all the world.

Superstition is rooted in a much deeper and more sensitive layer of the psyche than skepticism.

If you wish to advance into the infinite, explore the finite in all directions.