It has been the fault in teaching language, that learners have been limited to the mere forms of words, while the important duty of teaching them to look at the thing signified, has been entirely disregarded.  Hence they have only obtained book knowledge.  They know what the grammars say; but how to apply what they say, or what is in reality meant by it, they have yet to learn.  This explains the reason why almost every man who has studied grammar will tell you that “he used to understand it, but it has all gone from him, for he has not looked into a book these many years.”  Has he lost a knowledge of language?  Oh, no, he learned that before he saw a grammar, and will preserve it to the day of his death.  What good did his two or three years study of grammar do him?  None at all; he has forgotten all that he ever knew of it, and that is not much, for he only learned what some author said, and a few arbitrary rules and technical expressions which he could never understand nor apply in practice, except in special cases.  But I wander.  I throw in this remark to show you the necessity of bringing your minds to a close observance of things as they do in truth exist; and from them you can draw the principles of speech, and be able to use language correctly.  For we still insist on our former opinion, that all language depends on the permanent laws of nature, as exerted in the regulation of matter and mind.

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To return.  I have said that all action denotes power, cause, means, agency, and effects.

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Power depends on physical energy, or mental skill.  I have hinted at this fact before.  Things act according to the power or energy they possess.  Animals walk, birds fly, fishes swim, minerals sink, poisons kill.  Or, according to the adopted theories of naturalists: 

Minerals grow.

Vegetables grow and live.

Animals grow, and live, and feel.

Every thing acts according to the ability it possesses.  Man, possessed of reason, devises means and produces ends.  Beasts change locations, devour vegetables, and sometimes other beasts.  The lowest grade of animals never change location, but yet eat and live.  Vegetables live and grow, but do not change location.  They have the power to reproduce their species, and some of them to kill off surrounding objects.  “The carraguata of the West Indies, clings round,” says Goldsmith, “whatever tree it happens to approach; there it quickly gains the ascendant, and, loading the tree with a verdure not its own, keeps away that nourishment designed to feed the trunk, and at last entirely destroys its supporter.”  In our country, many gardens and fields present convincing proof of the ability of weeds to kill out the vegetables designed to grow therein.  You all have heard of the Upas, which has a power sufficient to destroy the lives of animals and vegetables for a large distance around.  Its very exhalations are death to whatever approaches it.  It serves in metaphor to illustrate the noxious effects of all vice, of slander and deceit, the effects of which are to the moral constitution, what the tree itself is to natural objects, blight and mildew upon whatever comes within its reach.