Know is an irregular active-transitive verb, from know, knew, knowing, known; found in the infinitive mood, present tense—­no person, or number:  and is governed by to; according to Rule 18th, which says, “The infinitive mood is governed in general by the preposition TO, which commonly connects it to a finite verb.”  Because the meaning is—­to know.

His is a personal pronoun, representing man, in the third person, singular number, and masculine gender; according to Rule 10th, which says, “A pronoun must agree with its antecedent, or the noun or pronoun which it represents, in person, number, and gender:”  and is in the possessive case, being governed by duty; according to Rule 4th, which says, “A noun or a pronoun in the possessive case, is governed by the name of the thing possessed.”  Because the meaning is—­his duty;—­i. e., the young man’s duty.

Duty is a common noun, of the third person, singular number, neuter gender, and objective case:  and is governed by know; according to Rule 5th, which says, “A noun or a pronoun made the object of an active-transitive verb or participle, is governed by it in the objective case.”  Because the meaning is—­to know his duty.

And is a copulative conjunction:  and connects the phrase which follows it, to that which precedes; according to Rule 22d, which says, “Conjunctions connect words, sentences, or parts of sentences.”  Because the meaning is—­studious to know his duty, and honestly bent, &c.

Honestly is an adverb of manner:  and relates to bent; according to Rule 21st, which says, “Adverbs relate to verbs, participles, adjectives, or other adverbs.”  Because the meaning is—­honestly bent.

Bent is a perfect participle, from the redundant active-transitive verb, bend, bent or bended, bending, bent or bended:  and relates to man; according to Rule 20th, which says, “Participles relate to nouns or pronouns, or else are governed by prepositions.”  Because the meaning is—­man bent. On is a preposition:  and shows the relation between bent and doing; according to Rule 23d, which says, “Prepositions show the relations of words, and of the things or thoughts expressed by them.”  Because the meaning is—­bent on doing.

Doing is an imperfect participle, from the irregular active-transitive verb, do, did, doing, done:  and is governed by on; according to Rule 20th, which says, “Participles relate to nouns or pronouns, or else are governed by prepositions.”  Because the meaning is—­on doing.

It is a personal pronoun, representing duty, in the third person, singular number, and neuter gender; according to Rule 10th, which says, “A pronoun must agree with its antecedent, or the noun or pronoun which it represents, in person, number, and gender:”  and is in the objective case, being governed by doing; according to Rule 5th, which says, “A noun or a pronoun made the object of an active-transitive verb or participle, is governed by it in the objective case.”  Because the meaning is—­doing it;—­i. e., doing his duty.