To properly describe "yourself" it is important to understand the component parts of the word: [quote]your Old English eower, possessive pronominal adjective, genitive of ge "ye" (see ye), from Proto-Germanic base of you. Cognate with Old Saxon iuwar, Old Frisian iuwer, Old Norse yðvarr, Old High German iuwer, German euer, Gothic izwar "your." Used in titles of honor by mid-14c.[/quote] https://www.etymonline.com/word/your [quote]self (pron.) Old English self, seolf, sylf "one's own person, -self; own, same," from Proto-Germanic *selbaz (source also of Old Norse sjalfr, Old Frisian self, Dutch zelf, Old High German selb, German selb, selbst, Gothic silba), Proto-Germanic *selbaz "self," from PIE *sel-bho-, suffixed form of root *s(w)e-, pronoun of the third person and reflexive (referring back to the subject of a sentence), also used in forms denoting the speaker's social group, "(we our-)selves" (see idiom). Trying to define yourself is like trying to bite your own teeth. [Alan Watts] Its use in compounds to form reflexive pronouns grew out of independent use in Old English. As a noun from early 14c.[/quote] https://www.etymonline.com/word/self These combine to form: [quote]yourself by early 14c., from your + self. Plural yourselves first recorded 1520s.[/quote] https://www.etymonline.com/word/yourself