We go forth at the evening hour and look upon the sun sinking beneath the horizon; we mark the varying hues of light as they appear, and change, and fade away. We see the shades of night approaching, with a gradual pace, till the beautiful landscape on which we had been gazing, the hills and the meadows; the farm house and the cultivated fields, the grove, the orchard, and the garden; the tranquil lake and the babbling brook; the dairy returning home, and the lambkins gambolling beside their dams; all recede from our view, and appear to us no longer. All this is relative action. But so far as language and ideas are concerned, it matters not whether the sun actually sinks behind the hills, or the hills interpose between it and us; whether the landscape recedes from our view, or the shades of night intercept so as to obscure our vision. The habit of thought is the same, and the form of expression must agree with it. We say the sun rises and sets, in reference to the obvious fact, without stopping to inquire whether it really moves or not. Nor is such an inquiry at all necessary, as to matter of fact, for all we mean by such expressions, is, that by some process, immaterial to the case in hand, the sun stands in a new relation to the earth, its altitude is elevated or depressed, and hence the action is strictly relative. For we should remember that rising and setting, up and down, above and below, in reference to the earth, are only relative terms.

We speak and read of the changes of the moon, and we correctly understand each other. But in truth the moon changes no more at one time than at another. The action is purely relative. One day we observe it before the sun, and the next behind it, as we understand these terms. The precise time of the change, when it will appear to us in a different relation to the sun, is computed by astronomers, and set down in our almanacs; but it changes no more at that time than at any other, for like every thing else, it is always changing.

In a case we mentioned in a former lecture, "John looks like or resembles his brother," we have an example of relative action. So in the case of two men travelling the same way, starting together, but advancing at different rates; one, we say, falls behind the other. In this manner of expression, we follow exactly the principles on which we started, and suit our language to our ideas and habits of thinking. By the law of optics things are reflected upon the retina of the eye inversely, that is, upside down; but they are always seen in a proper relation to each other, and if there is any thing wrong in the case, it is overcome by early habit; and so our language accords with things as they are manifested to our understandings.

These examples will serve to illustrate what we mean by relative action, when applied to natural philosophy or the construction of language.

I had intended in this lecture to have treated of the agents and objects of verbs, to prove, in accordance with the first and closest principles of philosophy, that every "cause must have an effect," or, in other words, that every action must terminate on some object, either expressed or necessarily understood; but I am admonished that I have occupied more than my usual quota of time in this lecture already, and hence I shall leave this work for our next.

I will conclude by the relation of an anecdote or two from the life of that wonderful man, Gallileo Gallilei, who was many years professor of mathematics at Padua. Possessed of a strong, reflecting mind, he had early given his attention to the observation of things, their motions, tendencies, and power of resistance, from which he ascended, step by step, to the sublime science of astronomy. Being of an honest and frank, as well as benevolent disposition, he shunned not to state and defend theories at war with the then received opinions. All learning was, at that time, in the hands or under the supervision of the ecclesiastics, who were content to follow blindly the aristotelian philosophy, which, in many respects, was not unlike that still embraced in our neuter verb systems of grammar. There was a sworn hostility against all improvement, or innovation as it was called, in science as well as in theology. The copernican system, to which Gallileo was inclined, if it had not been formally condemned, had been virtually denounced as false, and its advocates heretical. Hence Gallileo never dared openly to defend it, but, piece by piece, under different names, he brought it forth, which, carried out, would establish the heretical system. Dwelling as a light in the midst of surrounding darkness, he cautiously discovered the precious truths revealed to his mind, lest the flood of light should distract and destroy the mental vision, break up the elements of society, let loose the resistless powers of ignorance, prejudice and bigotry, and envelope himself and friends in a common ruin. At length having prepared in a very guarded manner his famous "Dialogues on the Ptolmaic and Copernican Systems," he obtained permission, and ventured to publish it to the world, altho an edict had been promulgated enjoining silence on the subject, and he had been personally instructed "not to believe or teach the motion of the earth in any manner."

By the false representation of his enemies, suspicions were aroused and busily circulated prejudicial to Gallileo. Pope Urban himself, his former friend, became exasperated towards him, and a sentence against him and his books was fulminated by the Cardinals, prohibiting the "sale and vending of the latter, and condemning him to the formal prison of the Holy Office for a period determined at their pleasure." The sentence of the Inquisition was in part couched in these words—"We pronounce, judge, and declare, that you, the said Gallileo, by reason of these things, which have been detailed in the course of this investigation, and which, as above, you have confessed, have rendered yourself vehemently suspected by this Holy Office, of heresy; that is to say, that you believe and hold the false doctrine, and contrary to the Holy and Divine Scriptures, namely, that the sun is the center of the world, and that it does not move from east to west, and that the earth does move, and is not the center of the world; also, that an opinion can be held and supported as probable, after it has been declared, and finally decreed contrary to the Holy Scriptures"—by the Holy See!! "From which," they continue, "it is our pleasure that you be absolved, provided that, first, with a sincere heart, and unfeigned faith, in our presence, you abjure, curse, and detest the said errors and heresies, and every other error and heresy contrary to the Catholic and Apostolic Church of Rome, in the form now shown to you."

After suffering under this anathema some time, Gallileo, by the advice of his friends, consented to make a public abjuration of his former heresies on the laws of motion. Kneeling before the "Most Eminent and Most Reverend Lords Cardinals, General Inquisitors of the universal Christian republic, against heretical depravity, having before his eyes the Holy Gospels," he swears that he always "believed, and now believes, and with the help of God, will in future believe, every article which the Holy Catholic Church of Rome holds, teaches, and preaches"—that he does altogether "abandon the false opinion which maintains that the 'sun is the center of the world, and that the earth is not the center and movable,' that with a sincere heart and unfeigned faith, he abjures, curses, and detests the said errors and heresies, and every other error and sect contrary to the said Holy Church, and that he will never more in future, say or assert any thing verbally, or in writing, which may give rise to similar suspicion." As he arose from his knees, it is said, he whispered to a friend standing near him, "E pur si muove"—it does move, tho.

In our times we are not fated to live under the terrors of the Inquisition; but prejudice, if not as strong in power to execute, has the ability to blind as truly as in other ages, and keep us from the knowledge and adoption of practical improvements. And it is the same philosophy now, which asks if inanimate matter can act, which demanded of Gallileo if this ponderous globe could fly a thousand miles in a minute, and no body feel the motion; and with Deacon Homespun, in the dialogue, "why, if this world turned upside down, the water did not spill from the mill ponds, and all the people fall headlong to the bottomless pit?"

If there are any such peripatetics in these days of light and science, who still cling to the false and degrading systems of neutrality, because they are honorable for age, or sustained by learned and good men, and who will oppose all improvement, reject without examination, or, what is still worse, refuse to adopt, after being convinced of the truth of it, any system, because it is novel, an innovation upon established forms, I can only say of them, in the language of Micanzio, the Venetian friend of Gallileo—"The efforts of such enemies to get these principles prohibited, will occasion no loss either to your reputation, or to the intelligent part of the world. As to posterity, this is just one of the surest ways to hand them down to them. But what a wretched set this must be, to whom every good thing, and all that is found in nature, necessarily appears hostile and odious."