A man's knowledge may be said to be mature, in other words, when it has reached the most complete state of perfection to which he, as an individual, is capable of bringing it, when an exact correspondence is established between the whole of his abstract ideas and the things he has actually perceived for himself. His will mean that each of his abstract ideas rests, directly or indirectly, upon a basis of observation, which alone endows it with any real value; and also that he is able to place every observation he makes under the right abstract idea which belongs to it.
If the lives of men were relieved of all need, hardship and adversity; if everything they took in hand were successful, they would be so swollen with arrogance that, though they might not burst, they would present the spectacle of unbridled folly-nay, they would go mad. And I may say, further, that a certain amount of care or pain or trouble is necessary for every man at all times. A ship without ballast is unstable and will not go straight.
The fly ought to be used as the symbol of impertinence and audacity; for whilst all other animals shun man more than anything else, and run away even before he comes near them, the fly lights upon his very nose.
Still, instead of trusting what their own minds tell them, men have as a rule a weakness for trusting others who pretend to supernatural sources of knowledge.
To form a judgment intuitively is the privilege of few; authority and example lead the rest of the world. They see with the eyes of others, they hear with the ears of others. Therefore it is very easy to think as all the world now think; but to think as all the world will think thirty years hence is not in the power of every one.
If anyone spends almost the whole day in reading...he gradually loses the capacity for thinking...This is the case with many learned persons; they have read themselves stupid
Two Chinamen visiting Europe went to the theatre for the first time. One of them occupied himself with trying to understand the theatrical machinery, which he succeeded in doing. The other, despite his ignorance of the language, sought to unravel the meaning of the play. The former is like the astronomer, the latter the philosopher.