Ah is an interjection, indicating sorrow:  and is used independently; according to Rule 24th, which says, “Interjections have no dependent construction; they are put absolute, either alone, or with other words.”  Because the meaning is—­ah!—­unconnected with the rest of the sentence.

Poor is a common adjective, of the positive degree, compared regularly, poor, poorer, poorest:  and relates to nature; according to Rule 9th, which says, “Adjectives relate to nouns or pronouns.”  Because the meaning is—­poor human nature.

Fallen is a participial adjective, compared (perhaps) by adverbs:  and relates to nature; according to Rule 9th, which says, “Adjectives relate to nouns or pronouns.”  Because the meaning is—­fallen nature.

Human is a common adjective, not compared:  and relates to nature; according to Rule 9th, which says, “Adjectives relate to nouns or pronouns.”  Because the meaning is—­human nature.

Nature is a common noun, of the second person, singular number, neuter gender, and nominative case:  and is put absolute by direct address; according to Rule 8th, which says, “A noun or a pronoun is put absolute in the nominative, when its case depends on no other word.”  Because the meaning is—­poor fallen human nature!—­the noun being unconnected with any verb.

What is a pronominal adjective, not compared:  and relates to conflicts; according to Rule 9th, which says, “Adjectives relate to nouns or pronouns.”  Because the meaning is—­what conflicts.

Conflicts is a common noun, of the third person, plural number, neuter gender, and nominative case:  and is the subject of are; according to Rule 2d, which says, “A noun or a pronoun which is the subject of a finite verb, must be in the nominative case.”  Because the meaning is—­conflicts are.

Are is an irregular neuter verb, from be, was, being, been; found in the indicative mood, present tense, third person, and plural number:  and agrees with its nominative conflicts; according to Rule 14th, which says, “Every finite verb must agree with its subject, or nominative, in person and number.”  Because the meaning is—­conflicts are.

Thy is a personal pronoun, representing nature, in the second 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 possessive case, being governed by portion; 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—­thy portion.

Portion is a common noun, of the third person, singular number, neuter gender, and nominative case:  and is put after are, in agreement with conflicts; according to Rule 6th, which says, “A noun or a pronoun put after a verb or participle not transitive, agrees in case with a preceding noun or pronoun referring to the same thing.”  Because the meaning is—­conflicts are thy portion.