It is the characteristic of mind to be capable of improvement. An individual surrenders the best attribute of man, the moment he resolves to adhere to certain fixed principles, for reasons not now present to his mind, but which formerly were.1 The instant in which he shuts upon himself the career of enquiry is the instant of his intellectual decease. He is no longer a man; he is the ghost of departed man. 'There can be no scheme more egregiously stamped with folly than that of separating a tenet from the evidence upon which its validity depends. If I cease from the habit of being able to recall this evidence, my belief is no longer a perception, but a prejudice: it may influence me like a prejudice; but cannot animate me like a real apprehension of truth. The difference between the man thus guided and the man that keeps his mind perpetually alive is the difference between cowardice and fortitude. The man who is, in the best sense, an intellectual being delights to recollect the reasons that have convinced him, to repeat them to others, that they may produce conviction in them, and stand more distinct and explicit in his own mind; and, he adds to this a willingness to examine objections, because he takes no pride in consistent error. The man who is not capable of this salutary exercise, to what valuable purpose can he be employed? Hence it appears that no vice can be more destructive than that which teaches us to regard any judgement as final, and not open to review. The same principle that applies to individuals applies to communities, There is no proposition at present apprehended to be true so valuable as to justify the introduction of an establishment for the purpose of inculcating it on mankind. Refer them to reading, to conversation, to meditation; but teach them neither creeds nor catechisms, either moral or political.
1Book 1, Chap. V, p. 127.
To Book VI, Chapter IX.