Those who style themselves philosophers and have written upon the subject of the mind have always considered the soul as constituting a nature which is one and indivisible; yet for the purpose of more fully understanding its various stages of action, they have given it three parts or views in which it may be contemplated, expressed in the Intellect, Sensibilities and the Will; or the intellectual, sensitive and voluntary states of the mind.
We find in different languages terms expressive of these three states. Different authors, in works not written expressly upon the subject of the mind, have adopted these modes of expressing its action.
The popular author of "Literary Hours" [Nathan Drake] has given in one of his works an interesting biographical sketch of Sir Robert Steele. After referring to his repeated seasons of riot and revelry, of his determinations and repentances, etc., he thus describes him,
"His misfortune, the cause of all his errors, was not to have clearly seen where his deficiencies lay; they were neither of the head nor of the heart, but of the volition. He possessed the wish, but not the power of volition to carry his purposes into execution."
It has been remarked of Burns, that the force of that remarkable poet lay in the power of his understanding and the sensibilities of his heart.
Dr. Currie, in his life of Burns, makes use of the following language:
"He knew his own failings and predicted their consequences; these melancholy forebodings were not long absent from his mind; yet his passions carried him down the stream of error and swept him over the precipice he saw directly in his course. The fatal defect of his character lay in the comparative weakness of his volition; which governing the conduct according to the dictates of the understanding, entitles it to be denominated rational."
Professor Upham, in his philosophy, informs us of a celebrated writer, who in giving directions to his son as to the manner of conducting with foreign ministers, uses the following language:
"If you engage his heart, you have a fair chance of imposing upon his understanding and determining his will."
Shakespeare, the great philosopher of the human understanding, says in the second scene of Hamlet:
"It shows a will most incorrect to heaven, a heart unfortified, an understanding simple and unschooled."