82. He that can swim needs not despair to fly; for to swim is to fly in a grosser fluid, and to fly is to

swim in a subtler.

83. The Helvetii, if they went through the country of the Sequani, were sure to meet with various difficulties; and if they went through the Roman province, they were exposed to the danger of opposition from Cæsar; but they were obliged to go one way or the other; therefore they were either sure of meeting with various difficulties, or exposed to the danger of opposition from Cæsar.-De Bello Gallico, lib. I. 6.

84. Riches are for spending, and spending for honour and good actions; therefore extraordinary expense must be limited by the worth of the occasion.-Bacon.

85. If light is not refracted near the surface of the moon, there cannot be any twilight; but if the moon has no atmosphere light is not refracted near its surface; therefore if the moon has no atmosphere there cannot be any twilight. 86. The preservation of society requires exchange; whatever requires exchange requires equitable valuation of property; this requires the adoption of a common measure; hence the preservation of society requires the adoption of a common

measure.

87. The several species of brutes being created to prey upon one another proves that the human species were intended to prey upon them. 88. The more correct the logic, the more certainly the conclusion will be wrong if the premises are false. Therefore where the premises are wholly uncertain, the best logician is the least safe guide.

89. If our rulers could be trusted always to look to the best interests of their subjects, monarchy would be the best form of government; but they cannot be trusted; therefore monarchy is not the best form of government.

90. If men were prudent, they would act morally for their own good; if benevolent, for the good of others. But many men will not act morally, either for their own good, or that of others; such men, therefore, are not prudent or benevolent. 91. He who bears arms at the command of the magis-* trate does what is lawful for a Christian; the Swiss in the French service, and the British in the American service, bore arms at the command of the magistrate; therefore they did what was lawful for a Christian.-Whately.

92. A man that hath no virtue in himself ever envieth virtue in others; for men's minds will either feed upon their own good or upon others' evil; and who wanteth the one will prey upon the other.— Bacon.

93. The object of war is durable peace; therefore soldiers are the best peace-makers.

94. Confidence in promises is essential to the intercourse of human life; for without it the greatest part of our conduct would proceed upon chance. But there could be no confidence in promises, if men were not obliged to perform them; the obligation, therefore, to perform promises is essential to the same ends and in the same degree.

95. If the majority of those who use public-houses are prepared to close them, legislation is unnecessary; but if they are not prepared for such a measure, then to force it on them by outside pressure is both dangerous and unjust.

96. He who believes himself to be always in the right in his opinion, lays claim to infallibility; you always believe yourself to be in the right in your opinion; therefore you lay claim to infallibility. -Whately.

97. If we never find skins except as the teguments of animals, we may safely conclude that animals cannot exist without skins. If colour cannot exist by itself, it follows that neither can anything that is coloured exist without colour. So, if language without thought is unreal, thought without language must also be so.

98. No soldiers should be brought into the field who are not well qualified to perform their part; none but veterans are well qualified to perform their part; therefore none but veterans should be brought into the field.-Whately.

99. The minimum visibile is the least magnitude which can be seen; no part of it alone is visible, and yet all parts of it must affect the mind in order that it may be visible; therefore, every part of it must affect the mind without being visible. 100. The scarlet poppy belongs to the genus Papaver, of the natural order Papaveraceæ; which again is part of the subclass Thalamifloræ, belonging to the great class of Dicotyledons. Hence the scarlet poppy is one of the Dicotyledons.

101. Improbable events happen almost every day; but what happens almost every day is a very probable event; therefore improbable events are very probable events.—Whately.

LESSON XXII.—Quantification of the Predicate. 1. What does the quantification of the predicate mean?

2. Assign to each of the following propositions its proper symbol, and the symbol of its converse: (1) Knowledge is power.

*

(2) Some rectangles are all squares.

(3) Only the honest ultimately prosper.

(4) Princes have but their titles for their glories.

(5) In man there is nothing great but mind.

(6) The end of philosophy is the detection of unity. 3. Draw all the contrapositive propositions and immediate inferences you can from the following propositions:

(1) London is a great city.

(2) London is the capital of England.

(3) All ruminant animals are all cloven-footed animals.

(4) Some members of parliament are all the minis

ters.

4. Write out in Hamilton's notation the moods Baroko, Darapti, Felapton, Bokardo.

LESSON XXIII.-Boole's System of Logic.

1. Apply this system of inference to prove the syllogisms on p. 141, in Cesare, and Camestres. 2. Show that if all A's are not B's, then no B's are A's; and that if all A's are all B's, then all not A's are all not B's.

3. Develope the term substance, as regards the terms vegetable, animal, organic; then select the com. binations which agree with these premises:

"What is vegetable is not animal but is organic; what is animal is organic.”

4. Test the validity of this argument: "Good always triumphs, and vice always fails; therefore the victor cannot be wrong, nor the vanquished right."

5. It is known of a certain class of things that— (1) Where the quality A is, B is not.

(2) Where B is, and only where B is, C and D are. What can we infer from these premises of

the class of things in which A is not present but C is present?

6. If all A's are B's; all B's are C's; all C's are D's ; shew that all A's are D's, and that all not D's are not A's.

LESSON XXIV.-Method.

1. What is the supposed position of method according to former logical writers, and what are the rules of method?

2. Explain the expressions nobis notiora, and notiora naturæ.

3. Of what kind is the usual method of instruction? 4. Prove that analysis in extension is synthesis in intension, using some of the series of terms in Question 6, Lesson v. as illustrations.

5. Explain the exact meanings of the expressions à priori and à posteriori knowledge.

6. To which kind belongs our knowledge of the following facts?

(1) The light of the stars takes a long time to reach us.

(2) Vaccination is a preservative against small-pox. (3) A meteor becomes heated in passing through the air.

(4) There must be either some inhabitants or no inhabitants upon Jupiter.

LESSON XXV.—Perfect Induction.

1. Define and distinguish Deduction, Induction, and Traduction.