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frame. Optics explains the manner in which vision is effected, assigns the reasons of the several alterations which the rays of light undergo in the eye, and shows by what causes objects appear at different times greater or smaller, more distinct or confused, nearer or more remote. In this extensive signification, the science is considered by Sir Isaac Newton in his work on this subject. Optics is commonly divided into two parts : Dioptrics, under which term is included whatever relates to the appearance of bodies seen through transparent substances, as fish in water ; and Catoptrics, from a Greek word, signifying a looking-glass, which relates to seeing bodies by reflected light. To these may be added a third, which treats of the causes and varieties of colours, observable in all bodies. The more the properties of light are investigated, the more astonishing they appear. A succession of the particles, following each other in a straight line, is called a ray of light; and this ray, in whatever manner its direction may be changed, whether by refraction, reflection, or inflection, always preserves a rectilinear course till it be again changed ; neither is it possible to make it move in the arch of a circle, ellipsis, or other curve. As a proof of this, we cannot see objects through a crooked tube.
LESSON 13.-Sequence of Sentences. 41. Rule 10. — The sentences belonging to the same paragraph should appear, as it were, to grow out of one another, forming a necessary part in the same train of reasoning. Thus, the second sentence should form an appropriate sequel to the first, the third to the second, and so on to the conclusion of the paragraph. The natural sequence of sentences forms one of the principal difficulties in the art of composition. Perhaps the justness of this observation will be rendered more apparent by attention to the following illustration, which is as applicable to narrative and descriptive pieces, as to any other kind of writing.
ON FLATTERY. 1. Flattery is false praise ; and is either offered to those by whom it is altogether unmerited, or is given to an extent beyond what truth can authorise. 2. A mind open to flattery is always in a dangerous situation. 3. No disposition can be more detrimental to youth than a love of flattery.
REMARKS.-On examining the previous paragraph, it will be seen that though all the sentences relate to the same subject, they are not parts of the same continuous train of thought, but are entirely independent of one another. However suitable this mode of writing might be for maxims and proverbs, it is altogether inconsistent with a regular discourse. If we wish to write with effect, we must avoid running from one remark to another which has no immediate relation with it. On the contrary, we must consider how the proposition with which we commenced can be confirmed by additional reasons leading to the same purpose.
We shall now subjoin a passage constructed according to the rule, in which the train of thought suggested by each sentence is carried out in the one following:
1. Flattery is false praise ; and is either offered to those by whom it is altogether unmerited, or is given to an extent beyond what truth can authorise. In either case, reprehension is due to those by whom it is administered, and contempt to those by whom it is received.
REMARK. - In the paragraph thus completed, the second sentence is a proper sequel to the first, and the two form an appropriate introduction to what follows.
2. A mind open to flattery is always in a dangerous situation ; it credits whatever is spoken in its praise, and must, therefore, think those who do not offer the incense of adulation, are either blind to its merits, or envy them; this produces the arrogance, ill pature, and self-sufficiency, which are almost inseparable from such persons, and frequently urges them to the most ridiculous expedients to tempt others to flatter them. So far as this over-fondness for praise operates, it must retard our improvement; for, who will strive to gain any new accomplishment, who believes he is already accomplished ? Who will endure the labour of acquiring advantages, who is told either that he does not want them, or that he has them already ?
REMARK.- From what has been advanced, we are enabled to draw the following conclusion:
3. No disposition, therefore, can be more detrimental to youth, than a love of flattery ; both as it may prevent their
ovement, and make them too fond of the person who pretends to admire them, who may always be suspected of some vile and disingenuous purpose ; for those who basely violate truth by gross flattery can scarcely be supposed to possess any virtue.
42. RULE 11. Connection of Sentences. - In the connection of sentences with one another, care must be had to avoid the use of unnecessary relatives and conjunctions. They cannot be altogether dispensed with ; nor can any rule be given for their appropriate application on all occasions. In this respect, good taste, and an harmonious ear, will form the best guide.
QUESTIONS.—Quote the Rule for the Sequence of Sentences. Adduce the example given of the violation of this rule. Point out the impropriety of such sentences. Adduce the example in which the rule has been observed. Quote the Rule for the Connection of Sentences.
VARIETY OF EXPRESSION.
LESSON 14. 43. The same idea, or nearly the same, may be expressed by a variety of forms; as will be exhibited in the following rules.
RULE 1. - In the structure of sentences, the unnecessary use of the conjunction and should be avoided. The same sense may, in general, be expressed by the present active, the perfect, or the present passive participle.
a. EXAMPLE WITH THE PRESENT ACTIVE PARTICIPLE.-" I walked out yesterday in the open fields, and night insensibly fell upon me.” Better expressed thus : “Walking out yesterday in the open fields, night insensibly fell upon me.”
b. EXAMPLE WITH THE PRESENT PASSIVE PARTICIPLE.-“The blueness of the ether was exceedingly heightened and enlivened by the season of the year, and the galaxy appeared in its most beautiful white.” Better thus : “ The blueness of the ether being exceedingly heightened and enlivened by the season of the year, the galaxy appeared in its most beautiful white.”
EXERCISES. — Substitute the participle for the conjunction wherever it is suitable ;
1. Most of his attempts have failed, and he has ceased to plan new ones.
2. Alexander the Great ascended the throne, and was eager to pursue the ambitious projects of his father with regard to Persia.
3. He was called to the exercise of the sovereign power at an early age, and evinced a great knowledge of government and laws.
4. Bernard was armed with the authority of the pope, and fanned the flame of military fanaticism.
5. I fixed my eyes on different objects, and I soon perceived that I had the power of losing and recovering them, and that I could at pleasure destroy and renew this beautiful part of my existence.
44. RULE 2.—The nominative case absolute may frequently be employed instead of the verb and conjunction.
Thus, instead of saying, “The officer seized the favourable opportunity, and succeeded in his enterprize;" we may say, “ The officer having seized the favourable opportunity, succeeded in his enterprize.”
EXERCISES. — Substitute the case absolute for the verb and conjunction in the following sentences ;
1. He returned from the excursion and diligently employed the remainder of the evening in study.
2. The waters of the lake were swollen by the continued rains, and the Neva inundated the city of Petersburg, and swept away the houses on its banks.
3. The evidence and the sentence were stated ; and the president put the question, whether a pardon should be granted.
4. The request was refused, and the breach was widened by the obstinacy of both parties.
5. The deposed monarch was not well treated by the Earl of Leicester, and the public sympathy began to be manifested in his behalf
LESSON 15. 45. Rule 3.-The transitive verb may be changed into the passive, and the passive into the transitive, without altering the sense.
Thus, " The authority of the Romans superseded that of the Druids,"