The concluding words of Book 1 of Petrarch’s Secretum.  Translation is the Gutenberg by William Draper, though I’ve been reading the I Tatti Library dual-language edition by Nicholas Mann.

Augustine: . Hec tibi pestis nocuit; hec te, nisi provideas perditum ire festinat. Siquidem fantasmatibus suis obrutus, multisque et variis ac secum sine pace pugnantibus curis animus fragilis oppressus, cui primum occurrat, quam nutriat, quam perimat, quam repellat, examinare non potest; vigorque eius omnis ac tempus, parca quod tribuit manus, ad tam multa non sufficit. Quod igitur evenire solet in angusto multa serentibus, ut impediant se sata concursu, idem tibi contingit, ut in animo nimis occupato nil utile radices agat, nichilque fructiferum coalescat; tuque inops consilii modo huc modo illuc mira fluctuatione volvaris, nusquam integer, nusquam totus. Hinc est ut quotiens ad hanc cogitationem mortis aliasque, per quas iri possit ad vitam, generosus, si sinatur, animus accessit, inque altum naturali descendit acumine, stare ibi non valens, turba curarum variarum pellente, resiliat. Ex quo fit ut tam salutare propositum nimia mobilitate fatiscat, oriturque illa intestina discordia de qua multa iam diximus, illaque anime sibi irascentis anxietas, dum horret sordes suas ipsa nec diluit, vias tortuosas agnoscit nec deserit, impendensque periculum metuit nec declinat.
Francesco: . Heu mi misero! Nunc profunde manum in vulnus adegisti.

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S. Augustine. This, then, is that plague that has hurt you, this is what will quickly drive you to destruction, unless you take care. Overwhelmed with too many divers impressions made on it, and everlastingly fighting with its own cares, your weak spirit is crushed so that it has not strength to judge what it should first attack or to discern what to cherish, what to destroy, what to repel; all its strength and what time the niggard hand of Fate allows are not sufficient for so many demands. So it suffers that same evil which befalls those who sow too many seeds in one small space of ground.

As they spring up they choke each other. So in your overcrowded mind what there is sown can make no root and bear no fruit. With no considered plan, you are tossed now here now there in strange fluctuation, and can never put your whole strength to anything. Hence it happens that whenever the generous mind approaches (if it is allowed) the contemplation of death, or some other meditation that might help it in the path of life, and penetrates by its own acumen to the depths of its own nature, it is unable to stand there, and, driven by hosts of various cares, it starts back. And then the work, that promised so well and seemed so good, flags and grows unsteady; and there comes to pass that inward discord of which we have said so much, and that worrying torment of a mind angry with itself; when it loathes its own defilements, yet cleanses them not away; sees the crooked paths, yet does not forsake them; dreads the impending danger, yet stirs not a step to avoid it.

Petrarch. Ah, woe is me! Now you have probed my wound to the quick.