The subject of this work has long been thought to be that of the Good Shepherd, a theme that Tanner returned to frequently throughout his career. However, close study of this depiction suggests that the subject of this work may in fact be Joachim Leaving the Temple. According to scripture, Joachim was a herdsman who, at the age of twenty, took Anna, future mother of the Virgin Mary, as his wife. The couple lived together for fifty years without producing offspring. Still hopeful, they vowed that if they could ever conceive, their child's life would be dedicated to the service of the Lord. Joachim went to the temple, consulted the registers of the twelve tribes of Israel, and learned that all virtuous men had produced children. He retreated from the temple and took his flocks deep into the mountains, vowing to fast and pray for progeny. Those prayers were answered when the angel Gabriel appeared to Anna and Joachim, announcing that a child would be born to them. Tanner's composition remains highly unusual and mysterious with its references to classical, Orientalist, and biblical sources. The work's strained academicism suggests that it may have been produced as a study for an illustration and executed early in Tanner's career. As a student, Tanner had been introduced to illustration by Thomas Eakins who taught the medium, along with photography, to his pupils at the Pennsylvania Academy of the Fine Arts. Although he demonstrated skill, Tanner only dabbled occasionally in illustration and did not explore further the full range of its artistic and technical possibilities.