Paulinus of Nola's epistle 23 possesses a singularity by providing a long evocation of hair. It is such a long explanation (10-43) that it could easily be compared either to a homily or a small treatise included into this letter. He is not the only author of his time to write about this topic: Emperor Julian had done it in his Misopogon (363) and Synesios of Cyrene in his Praise of baldness (398); but Paulinus's ep. 23 provides the sole long reflection about spiritual meanings of hair in the Latin Patristic literature. As Julian and Synesios refered to Hellenic mythology and History, one praising hairs and the other despising it, Paulinus examines Biblical characters in an exegetic way, and thus the Hebrew perception of long hair, he intends to put forth in a Christian one. It cannot be said a digression because this development takes place in a theological letter, where he preaches the nicean creed of both Christ's natures. This paper intends to present the many aspects of Paulinus' richly shaded conception of hair, which appears an important point of his allegoric - and poetical - exegesis, relied to both human and divine natures of Christ and Man. In this letter, he obviously gives birth to an original Christian trichology, new hair meaning new head, spirit, and life, thus proving that cosmetic is neither a futile topic, nor a secular one, but rather a really cosmic subject.