In his 1974 poem “High Windows,” looking longingly at the new freedoms of the kids, Philip Larkin writes, “And everyone young going down the long slide / To happiness, endlessly.” The exhibition “Eternal Youth,” funded by crowdsourcing, explores how youthful desires, or desires for youthfulness, persist in adulthood. While shooting both the youngest and oldest of adults, photographer Dan Hall discovered a commonality between them: loneliness. All profits from the exhibition will go to mental-health organizations. —C.J.F.