In stating the objections, that may be urged against our mental identity, by such metaphysical or Pyrrhonean antagonists, as those of whom Lord Shaftesbury speaks, I shall endeavour to exhibit the argument in as strong a light as possible, and in a manner that appears to me in some measure, new. It is surely unnecessary for me to warn you, that the argument, however specious, is a sophistical one; and the nature of the peculiar sophistry which it involves shall be afterwards pointed out to you. But I conceive it to be most important, in teaching you to reflect for yourselves,—by far the most important lesson which you can be taught,—that you should be accustomed to consider the force of objections that may be urged, as clearly by the force of that surer evidence which they oppose,—and that even sophistry itself, when it is to be exhibited and confuted, should, therefore, always be exhibited fairly. We pay truth a very easy homage, when we content ourselves with despising her adversaries. The duty which we owe to her is of a more manly kind. It is to gird ourselves for the battle,—to fit us for overcoming those adversaries, whenever they shall dare to present themselves in array; and this we cannot do, with absolute confidence, unless we know well the sort of arms, which they may use, strong or feeble as those arms may be. I can have no fear, that any argument of this kind, in whatever manner it may be stated, can have the slightest influence on your conviction; because it is directly opposed by a principle of our nature, which is paramount to all reasoning. We believe our identity, as one mind, in our feelings of to-day and our feelings of yesterday, as indubitably as we believe that the fire, which burned us yesterday, would, in the same circumstances, burn us to-day,—not from reasoning, but from a principle of instant and irresistible belief, such as gives to reasoning itself all its validity. As Lord Shaftesbury justly says, “We act as resolutely, upon the mere supposition that we are, as if we had effectually proved it a thousand times.”
To identity, it may be said, it is necessary that the qualities be the same. That of which the qualities are different, cannot be the same; and the only mode of discovering whether a substance have the same or different qualities, is to observe, how it affects and is affected by other substances. It is recognized by us as the same, or, at least, as perfectly similar, when, in two corresponding series of changes, the same substances affect it in the same manner, and it affects, in the same manner, the same substances; and when either the same substances do not affect it in the same manner, or it does not affect, in the same manner, the same substances, we have no hesitation in considering it as different. Thus, if a white substance, resembling exactly, in every external appearance, a lump of sugar, do not melt when exposed to the action of boiling water, we do not regard it as sugar, because the water does not act on it as we have uniformly known it to act on that substance; or if the same white lump, in every other respect resembling sugar, affect our taste as bitter or acrid rather than sweet, we immediately, in like manner, cease to consider it as sugar, because it does not act upon our nerves of taste in the same manner as sugar acts upon them. The complete similarity, in other respects, is far from sufficient to make us alter our judgment; a single circumstance of manifest difference, in its mode either of acting upon other substances, or of being acted upon by them, being sufficient to destroy the effect of a thousand manifest resemblances.
Let this test of identity, then, it may be said, be applied to the mind, at different periods, if the test be allowed to be a just one; and let it be seen, whether, in the series of changes in which it acts or is acted upon, the phenomena precisely correspond in every case. If the same objects do not act upon it in the same manner, it must then be different, according to the very definition to which we are supposed to have assented.—You, of course, understand, that I am at present only assuming the character of an objector, and that I state an argument, the principle of which you will afterwards find to be false.
When we compare the listless inactivity of the infant, slumbering, from the moment at which he takes his milky food, to the moment at which he awakes to require it again, with the restless energies of that mighty being which he is to become, in his maturer years, pouring truth after truth in rapid and dazzling profusion, upon the world, or grasping in his single hand the destiny of empires, how few are the circumstances of resemblance which we can trace, of all that intelligence which is afterwards to be displayed, how little more is seen, than what serves to give feeble motion to the mere machinery of life. What prophetic eye can venture to look beyond the period of distinct utterance, and discern that variety of character by which even boyhood is marked, far less are the intellectual and moral growth of the years that follow—the genius, before whose quick glance the errors and prejudices, which all the ages and nations of mankind have received as truths, are to disappear—the political wisdom, with which, in his calm and silent meditations, he is to afford more security to his country than could be given to it by a thousand armies, and which, with a single thought, is to spread protection and happiness to the most distant lands—or that ferocious ambition, with which, in unfortunate circumstances of power, he is perhaps to burst the whole frame of civil society, and to stamp, through every age, the deep and dark impression of his existence, in the same manner as he leaves on the earth which he has desolated, the track of his sanguinary footsteps. The cradle has its equality almost as the grave. Talents, imbecilities, virtues, vices, slumber in it together, undistinguished; and it is well that it is so, since, to those who are most interested in the preservation of a life that would be helpless but for their aid, it leaves those delightful illusions which more than repay their anxiety and fatigue, and allows them to hope, for a single being, every thing which it is possible for the race of man to become. If clearer presages of the future mind were then discoverable, how large a portion of human happiness would be destroyed by this single circumstance! What pleasure could the mother feel, in her most delightful of offices, if she knew that she was nursing into strength, powers, which were to be exerted for the misery of that great or narrow circle, in which they were destined to move, and which to her were to be a source, not of blessing, but of grief, and shame, and despair!
“These shall the fury passions tear,
The vultures of the mind,”
says Gray, on thinking of a group of happy children;
“For see, how all around them wait,