Covering Up Sins

Quid est quod Sem et Japheth imposuerunt vestimentum super humeros suos, et perrexerunt retrorsum, et operuerunt nudum patrem, et non viderunt nudationem ejus? Littera evidentem pietatis expressit affectum, quod nudatum amictu patrem boni filii videre caverunt, ne paterna reverentia vel ipso minueretur aspectu. Siquidem etiam tacito vultu pietas frequenter offenditur. Unde etiam Romae vetus fuisse usus dicitur, ne filii cum parentibus et maxime puberes intrarent lavacrum. Sensus autem altior hoc habet, quia insipiens praesentia tantummodo videt quae in oculis sunt, futura non respicit, praeterita non cogitat. Sapiens autem et praeterita recordatur, et futura considerat. Omnis ergo mens sapiens retrorsum ambulat, hoc est, praeterita spectat; nec naturae quodam usu impeditur: nihil vacuum, nihil nudum suorum patitur esse gestorum. Operit quae aliter gesta sunt amictu quodam et gratia vel praesentis operis, vel futuri; ut nihil indecorum praetereat, nihil inornatum relinquat. Unde et Apostolus superiora obliviscebatur, priora appetebat: sed obliviscebatur, ut absconderet persecutionis errores, ut tegeret superiora delicta, bonisque operibus obumbraret. Beati enim et illi quorum tecta sunt peccata; id est, si tegantur bonis factis, et operiantur virtutum sequentibus disciplinis. Sanctus Ambrosius Mediolanensis, De Noe Et Arca, Caput XXXI Source: Migne PL 14.412d-413b

Why is it that Shem and Japeth placed the vestment on their shoulders and walked backward that they cover the nakedness of their father and not see his nakedness? 1 The bare letter expresses the affection of piety, that the good sons by use of the vestment are wary to look on their father's nudity, lest paternal reverence, or the appearance of it, be threatened, for certainly even a silent face may frequently offend. Whence it is said that it was an old custom of Rome that sons, and especially adolescents, not enter the baths with their parents. But this also has a higher meaning, that the unwise man sees only what is present before his eyes, not looking to the future or thinking on the past. For wise is he who remembers what has passed and considers the future. Thus every mind that is wise walks backward, that is, it looks on things of the past, not being impeded by the common way of nature, but suffering nothing worthless, nothing shameful to be associated with its own deeds. For he covers what is done otherwise with the cloak and grace of present works, or shall do, that nothing indecorous shall have been done, nor anything unfitting be left behind. Whence the Apostle Paul forgets things before, desiring things after, forgetting so that he might cover up the errors of persecution, and that he conceal past crimes beneath the shadow of good works. 2 For blessed are those whose sins are covered up; 3 that is, if they are covered up with good deeds, and obscured with the later exertions of virtue. Saint Ambrose, On Noah And The Ark, Chap 31 1 Gen 9.23 2 Phil 3.13-14 3 Ps 31.1