The strides of humanity are slow, they can only be counted in centuries.

I am impressed by the great limitations of the human mind. How quick are we to learn, that is, to imitate what others have done or thought before. And how slow to understand, that is, to see the deeper connections. Slowest of all, however, are we in inventing new connections or even in applying old ideas in a new field.

The opinions prevalent in one age, as truths above the reach of controversy, are confuted and rejected in another, and rise again to reception in remoter times. Thus the human mind is kept in motion without progress.

Looking at them, it does not seem as though even progress in intellect, slow as that also is, made the pace very much more rapid. When we look at those whose intellect is scarcely developed, they seem after each day of life to sink to sleep almost on the place they occupied the day before; and when we glance over those who are more highly evolved so far as intellect is concerned, they too are travelling very very slowly, and seem to make small progress in each day of life.

And lo! the creature did work slow in the brain.

Thought can never capture the movement of life, it is much too slow.

Humanity, like armies in the field, advances at the speed of the slowest.

My brain was slower than my mouth.

The human mind works at low efficiency. Twenty percent is the figure usually given.

...there is no real advance in human reason, for what we gain in one direction we lose in another; for all minds start from the same point, and as the time spent in learning what others have thought is so much time lost in learning to think for ourselves, we have more acquired knowledge and less vigor of mind. Our minds like our arms are accustomed to use tools for everything, and to do nothing for themselves.

...a timid reverence for the decisions of our ancestors, as if it were the nature of the mind always too degenerate and never to advance.

Pity me that the heart is slow to learn
What the swift mind beholds at every turn.

The human condition: lost in thought.

When the mind of man ceases to thrust outward, it begins to contract and wither.