If, then, by any process of instruction, discipline and mental force, we can influence our circumstances, banish grief and create cheerfulness, we can, in the same degree, reduce rules, for the pursuit of happiness, to a system; and make that system a matter of science. Can we not do this? The very million who deride the idea of seeking for enjoyment through the medium of instruction, unconsciously exercise the power in question to a certain extent--though not to the extent, of which they are capable. All those wise individuals, who have travelled with equanimity and cheerfulness through the diversified scenes of life, making the most of its good, and the least of its evils, bear a general testimony to the truth of this fact. We find in them a conviction that they had such power, and a force of character that enabled them to act according to their convictions. No person deserves the name of a philosopher, who is not wise in relation to the great purpose of life. In the same proportion, then, as I convince you, that by our own voluntary, physical and mental discipline, we can act upon circumstances, and influence our temperament, and thus bear directly upon our happiness, I shall be able to stir up your powers, and call forth your energy of character, to apply that discipline in your own case. In the same proportion I shall be instrumental in training you to the highest exercise of your reason, and the attainment of true philosophy. The elements upon which you are to operate, are your circumstances, habits, and modes of thinking and acting. The _philosopher of circumstances_[A] denies that you can act upon these. But, by his unwearied efforts to propagate his system, he proves, that he does not himself act upon his avowed convictions. The impulse of all our actions from birth to death, the spring of all our movements is a conviction, that we can alter and improve our condition. We have a consciousness stronger than our reason, that we can control our circumstances. We can change our regimen and habits; and by patience and perseverance, even our temperament. Every one can cite innumerable and most melancholy instances of those who have done it for evil. The habit of indulging in opium, tobacco, ardent spirits, or any of the pernicious narcotics, soon reduces the physical and mental constitution to that temperament, in which these stimulants are felt to be necessary. A corresponding change is produced in the mind and disposition. The frequent and regular use of medicine, though it may have been wholly necessary at first, finally becomes an inveterate habit. No phenomenon of physiology is more striking, than the facility with which the human constitution immediately commences a conformity to whatsoever change of circumstances, as of climate, habit, or aliment, we impose upon it. It is a most impressive proof, that the Creator has formed man capable of becoming the creature of all climates and conditions.