Doubts never end. If one doubt is removed, another takes its place. It is like removing the leaves of a tree one by one. Even if all the leaves are clipped off, new ones grow. The tree itself must be uprooted.
Sentiment: NEGATIVE
Doubt grows with knowledge.
Doubt begins only at the last frontiers of what is possible.
Test yourself on mankind. It is something that makes the doubter doubt, the believer believe.
Wonder rather than doubt is the root of all knowledge.
Doubt, the essential preliminary of all improvement and discovery, must accompany the stages of man's onward progress. The faculty of doubting and questioning, without which those of comparison and judgment would be useless, is itself a divine prerogative of the reason.
Doubt, indulged and cherished, is in danger of becoming denial; but if honest, and bent on thorough investigation, it may soon lead to full establishment of the truth.
To believe with certainty we must begin with doubting.
Doubt is not a pleasant condition, but certainty is absurd.
Doubt, of whatever kind, can be ended by action alone.
You can cut a tree down, and it grows back. Once a species goes, it's gone forever.