All life, animal and vegetable, seems in its essence like an effort to accumulate energy and then to let it flow into flexible channels, changeable in shape, at the end of which it will accomplish infinitely varied kinds of work. That is what the vital impetus, passing through matter, would fain do all at once. It would succeed, no doubt, if its power were unlimited, or if some reinforcement could come to it from without. But the impetus is finite, and it has been given once for all. It cannot overcome all obstacles. The movement it starts is sometimes turned aside, sometimes divided, always opposed; and the evolution of the organized world is the unrolling of this conflict.

No one who has ever brought up a child can doubt for a moment that love is literally the life-giving fluid of human existence.

Love is perfect kindness, which is born - there is no doubt - from the heart and eyes. The eyes make it blossom; the heart matures it.

Doubt the man who swears to his devotion.

In my religion there would be no exclusive doctrine; all would be love, poetry and doubt.

When the creation of a genius collide with the mind of a layman, and produce an empty sound, there is little doubt as to which is at fault.

Just think of the tragedy of teaching children not to doubt.

Doubt, indugled and cherished, is in danger of becoming denial; but if honest, and bent on thorough investigation, it may soon lead to dull establishment in the truth

Imperfect knowledge is the parent of doubt: thorough and honest research dispels it.

I have never heard anyone who I considered a good teacher claim that he or she is a good teacher - in the way that one might claim to be a good writer or surgeon or athlete. Self-doubt seems very much a part of the job of teaching: one can never be sure how well it is going.

Doubt is hell in the human soul.

Only when we know little do we know anything; doubt grows with knowledge.

Those only who know little can be said to know anything. The greater the knowledge the greater the doubt.

We know accurately only when we know little; with knowledge doubt increases.

Doubt indulged soon becomes doubt realized.

I have no doubt whatever that most people live, whether physically, intellectually, or morally, in a very restricted circle of their potential being. They make use of a very small portion of their possible consciousness and of their souls’ resources in general, much like a man who, out of his whole bodily organism, should get into a habit of using and moving only his little finger... We all have reservoirs of life to draw upon, of which we do not dream.

It need not discourage us if we are full of doubts. Healthy questions keep faith dynamic. In fact, unless we start with doubts we cannot have a deep-rooted faith. One who believes lightly and unthinkingly has not much of a belief. He who has a faith which is not to be shaken has won it through blood and tears - has worked his way from doubt to truth as one who reaches a clearing through a thicket of brambles and thorns.

I find no foeman in the road but fear; to doubt is failure and to dare success.

There are two ways to slide easily through life; to believe everything or doubt everything. Both ways save us from thinking.