(8) The opinion of Aristotle seemeth to me a negligent opinion, that of those things which consist by Nature, nothing can be changed by custom; using for example, that if a stone be thrown ten thousand times up it will not learn to ascend; and that by often seeing or hearing we do not learn to see or hear the better.  For though this principle be true in things wherein Nature is peremptory (the reason whereof we cannot now stand to discuss), yet it is otherwise in things wherein Nature admitteth a latitude.  For he might see that a strait glove will come more easily on with use; and that a wand will by use bend otherwise than it grew; and that by use of the voice we speak louder and stronger; and that by use of enduring heat or cold we endure it the better, and the like:  which latter sort have a nearer resemblance unto that subject of manners he handleth, than those instances which he allegeth.  But allowing his conclusion, that virtues and vices consist in habit, he ought so much the more to have taught the manner of superinducing that habit:  for there be many precepts of the wise ordering the exercises of the mind, as there is of ordering the exercises of the body, whereof we will recite a few.

(9) The first shall be, that we beware we take not at the first either too high a strain or too weak:  for if too high, in a diffident nature you discourage, in a confident nature you breed an opinion of facility, and so a sloth; and in all natures you breed a further expectation than can hold out, and so an insatisfaction in the end:  if too weak, of the other side, you may not look to perform and overcome any great task.

(10) Another precept is to practise all things chiefly at two several times, the one when the mind is best disposed, the other when it is worst disposed; that by the one you may gain a great step, by the other you may work out the knots and stonds of the mind, and make the middle times the more easy and pleasant.

(11) Another precept is that which Aristotle mentioneth by the way, which is to bear ever towards the contrary extreme of that whereunto we are by nature inclined; like unto the rowing against the stream, or making a wand straight by bending him contrary to his natural crookedness.

(12) Another precept is that the mind is brought to anything better, and with more sweetness and happiness, if that whereunto you pretend be not first in the intention, but tanquam aliud agendo, because of the natural hatred of the mind against necessity and constraint.  Many other axioms there are touching the managing of exercise and custom, which being so conducted doth prove indeed another nature; but, being governed by chance, doth commonly prove but an ape of Nature, and bringeth forth that which is lame and counterfeit.