Bernard Gui, Vita S. Thomae Aquinatis (=Fontes Vitae S. Thomae Aquinatis, ed. D. Prümmer, vol. 3, pp. 161-263), chap. 35, trans. Kenelm Foster, O.P. (The life of Saint Thomas Aquinas: biographical documents, trans. and edited by Kenelm Foster, O.P. (London: Longmans, Green and Co; Baltimore: Helicon Press, 1959), 53). Cf. Peter Calo, Vita S. Thomae Aquinatis (=Fontes Vitae S. Thomae Aquinatis, ed. D. Prümmer, vol. 1, pp. 17-55), chap. 21 (Deus in carne venit, Deus pro nobis mortuus), and especially William of Tocco, Ystoria sancti Thome de Aquino (=Fontes vitae S. Thomae Aquinatis, vol. 2, pp. 59-160), chap. 38:
Thanks to his force of soul, he feared no danger. . . .Nonetheless, he certainly had reason to fear such storms. For when he was still in early infancy, "A fearsome tempest swept suddenly down upon the castle of Roccasecca. Lightning struck the keep, killing his sister, who slept there, as well as the horses in the stable" (William of Tocco, Ystoria, chap. 3, as reproduced in L'histoire de saint Thomas d'Aquin de Gullaume de Tocco: traduction française du dernier état du texte (1323), avec introduction et notes par Claire le Brun-Gouanvic, Sagesses chrétiennes (Paris: Les Éditions du Cerf, 2005), 27 (90 for chap. 38); cf., for the Latin, Fontes, vol. 2, pp. 59-160 (where it is chap. 2), and Ystoria sancti Thome de Aquino de Guillaume de Tocco (1323): édition critique, introduction et notes, ed. Claire le Brun-Gouanvic (Toronto: Pontifical Institute of Medieval Studies, 1996), 98 (166 for chap. 38)).
It is said of him that as he made his way to Paris he had to suffer at sea a horrible tempest, at the hands of which even the mariners feared they would perish. And yet he showed no fear during this whole tempest. . . . In dreadful storms, thunder, and tempests, shielding himself with a sign of the cross as with a buckler he would say, 'God came in the flesh, God died for us [(Deus in carnem uenit, Deus pro nobis mortuus est)].'