We assume this ground, and we shall labor to maintain it, that every verb necessarily presupposes an agent or actor, an action, and an object acted upon, or affected by the action.
No action, as such, can be known to exist separate from the thing that acts. We can conceive no idea of action, only by keeping our minds fixed on the acting substance, marking its changes, movements, and tendencies. "The book moves." In this case the eye rests on the book, and observes its positions and attitudes, alternating one way and the other. You can separate no action from the book, nor conceive any idea of it, as a separate entity. Let the book be taken away. Where now is the action? What can you think or say of it? There is the same space just now occupied by the book, but no action is perceivable.
The boy rolls his marble upon the floor. All his ideas of the action performed by it are derived from an observation of the marble. His eye follows it as it moves along the floor. He sees it in that acting condition. When he speaks of the action as a whole, he thinks where it started and where it stopped. It is of no importance, so far as the verb is concerned, whether the marble received an impulse from his hand, or whether the floor was sufficiently inclined to allow it to roll by its own inherent tendency. The action is, in this case, the obvious change of the marble.
Our whole knowledge of action depends on an observance of things in a state of motion, or change, or exerting a tendency to change, or to counteract an opposing substance.
This will be admitted so far as material things are concerned. The same principle holds good in reference to every thing of which we form ideas, or concerning which we use language. In our definition of nouns we spoke of immaterial and imaginary things to which we gave names and which we consider as agencies capable of exerting an influence in the production of effects, or in resisting actions. It is therefore unimportant whether the action be real or imaginary. It is still inseparably connected with the thing that acts; and we employ it thus in the construction of language to express our thoughts. Thus, lions roar; birds sing; minds reflect; fairies dance; knowledge increases; fancies err; imagination wanders.
This fact should be borne in mind in all our attempts to understand or explain language. The mind should remain fixed to the acting substance, to observe its changes and relations at different periods, and in different circumstances. There is no other process by which any knowledge can be gained of actions. The mind contemplates the acting thing in a condition of change and determines the precise action by the altered condition of the thing, and thus learns to judge of actions by their effects. The only method by which we can know whether a vegetable grows or not is by comparing its form to-day with what it was some days ago. We can not decide on the improvement of our children only by observing the same rule.
"By their fruits ye shall know them," will apply in physics as well as in morals; for we judge of causes only by their effects. First principles can never be known. We observe things as they are, and remember how they have been; and from hence deduce our conclusions in reference to the cause of things we do not fully understand, or those consequences which will follow a condition of things as now existing. It is the business of philosophy to mark these effects, and trace them back to the causes which produced them, by observing all the intermediate changes, forms, attitudes, and conditions, in which such things have, at different times, been placed.
We say, "trees grow." But suppose no change had ever been observed in trees, that they had always been as they now are; in stature as lofty, in foliage as green and beautiful, in location unaltered. Who would then say, "trees grow?"
In this single expression a whole train of facts are taken into the account, tho not particularly marked. As a single expression we imply that trees increase their stature. But this we all know could never be effected without the influence of other causes. The soil where it stands must contain properties suited to the growth of the tree. A due portion of moisture and heat are also requisite. These facts all exist, and are indispensable to make good the expression that the "tree grows." We might also trace the capabilities of the tree itself, its roots, bark, veins or pores, fibres or grains, its succulent and absorbent powers. But, as in the case of the "man that killed the deer," noticed in a former lecture, the mind here conceives a single idea of a complete whole, which is signified by the single expression, "trees grow."
Let the following example serve in further illustration of this point. Take two bricks, the one heated to a high temperature, the other cold. Put them together, and in a short time you will find them of equal temperature. One has grown warm, the other cool. One has imparted heat and received cold, the other has received heat and imparted cold. Yet all this would remain forever unknown, but for the effects which must appear obvious to all. From these effects the causes are to be learned.