Origins
The legal profession preserves the oldest meaning of enjoy. When a contract says a tenant 'shall enjoy quiet possession', it does not mean they must find it delightful — it means they have the right to use it undisturbed. This possessive sense predates the emotional one.
Enjoy entered English from Old French enjoir, composed of en- ('in, make') and joir ('to enjoy, to have use of'), from Latin gaudēre — 'to rejoice, to be glad'. The Proto-Indo-European root *gāw- meant simply 'to rejoice'.
The Latin gaudēre produced two distinct English families. Through French it yielded joy, enjoy, and rejoice. Through learned Latin borrowing it produced gaudy — originally from gaudium ('joy'), used in English universities for a celebratory feast. A 'gaudy night' at Oxford was a festive occasion. Only later did gaudy shift to mean 'tastelessly ornate'.
Literary History
The emotional sense of enjoy — taking personal pleasure — solidified by the 16th century. Shakespeare used it freely in both senses: legal possession and emotional delight.
The Spanish cognate gozar and Italian godere preserve the same dual meaning. To enjoy, across all these languages, is both to possess and to take pleasure — a reminder that having and happiness were once treated as the same experience.