This substantive is the antecedent of the relative ([§ 11]).

Thus in [§ 143] the noun sailor is the antecedent of who.

Relative means “carrying back.” These pronouns are so called because they carry the mind back directly to the antecedent.

145. The simple relative pronouns are who, which, that, as, and what.

Who and which are declined as follows in both the singular and the plural:—

Nominativewhowhich
Possessivewhosewhose
Objectivewhomwhich

That, as, and what are not inflected. They have the same form for both nominative and objective and are not used in the possessive case.

146. As may be used as a relative pronoun when such stands in the main clause.

147. As is often used as a relative after the same.