A long habit of not thinking ...

A long habit of not thinking a thing wrong gives it a superficial appearance of being right.
A long habit of not thinking a thing wrong gives it a superficial appearance of being right.

More phrases

If one does not know to which port one is sailing, no wind is favorable.
What a distressing contrast there is between the radiant intelligence of the child and the feeble mentality of the average adult.
We are masters of the unsaid words, but slaves of those we let slip out.
I have always found that mercy bears richer fruits than strict justice.
A lie gets halfway around the world before the truth has a chance to get its pants on.

Quotes from the same author

The World is my country, all mankind are my brethren, and to do good is my religion.
The most formidable weapon against errors of every kind is reason.
Arms, like laws, discourage and keep the invader and plunderer in awe and preserve order.
The balance of power is the scale of peace. The same balance would be preserved were all the world not destitute of arms, for all would be alike; but since some will not, others dare not lay them aside ... Horrid mischief would ensue were one half the world deprived of the use of them ... the weak will become prey to the strong.
Arms discourage and keep the invader and plunderer in awe, and preserve order in the world as well as property... Horrid mischief would ensue were the law-abiding deprived of the use of them.