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.
It is only about things that do not interest one that one can give a really unbiased opinion, which is no doubt the reason why an unbiased opinion is always absolutely valueless.
If we didn't live venturously, plucking the wild goat by the beard, and trembling over precipices, we should never be depressed, I've no doubt; but already should be faded, fatalistic and aged.
Given the millions of billions of Earth-like planets, life elsewhere in the Universe without a doubt, does exist. In the vastness of the Universe we are not alone.