Every human being should be allowed to investigate to the extent of his desire—his ability. The literature of the world should be open to him—nothing prohibited, sealed or hidden. No subject can be too sacred to be understood. Each person should be allowed to reach his own conclusions and to speak his honest thought.
He who threatens the investigator with punishment here, or hereafter, is an enemy of the human race. And he who tries to bribe the investigator with the promise of eternal joy is a traitor to his fellow-men.
There is no real investigation without freedom—freedom from the fear of gods and men.
So, all investigation—all experiment—should be pursued in the light of reason.
Every man should be true to himself—true to the inward light. Each man, in the laboratory of his own mind, and for himself alone, should test the so-called facts—the theories of all the world. Truth, in accordance with his reason, should be his guide and master.
To love the truth, thus perceived, is mental virtue—intellectual purity. This is true manhood. This is freedom.
To throw away your reason at the command of churches, popes, parties, kings or gods, is to be a serf, a slave.
It is not simply the right, but it is the duty of every man to think—to investigate for himself—and every man who tries to prevent this by force or fear, is doing all he can to degrade and enslave his fellow-men.
Every Man Should be Mentally Honest.
He should preserve as his most precious jewel the perfect veracity of his soul.