Genius has been defined as 'the power of taking pains'; but hardly any one keeps up his interest in knowledge throughout a whole life.

The troubles of a family, the business of making money, the demands of a profession destroy the elasticity of the mind.

The waxen tablet of the memory which was once capable of receiving 'true thoughts and clear impressions' becomes hard and crowded; there is not room for the accumulations of a long life (Theaet.).

The student, as years advance, rather makes an exchange of knowledge than adds to his stores.
There is no pressing necessity to learn; the stock of Classics or History or Natural Science which was enough for a man at twenty-five is enough for him at fifty.

Neither is it easy to give a definite answer to any one who asks how he is to improve.