This is most interesting!

II-II q. 20 art. 4

WHETHER DESPAIR ARISES FROM ACEDIA

Reply to Objection 2. According to the Philosopher (Rhet. i, 11), just as hope gives rise to joy, so, when a man is joyful he has greater hope: and, accordingly, those who are sorrowful fall the more easily into despair, according to 2 Corinthians 2:7: "Lest . . . such an one be swallowed up by overmuch sorrow." Yet, since the object of hope is good, to which the appetite tends naturally, and which it shuns, not naturally but only on account of some supervening obstacle, it follows that, more directly, hope gives birth to joy, while on the contrary despair is born of sorrow.

Reply to Objection 3. This very neglect to consider the Divine favors arises from sloth. For when a man is influenced by a certain passion he considers chiefly the things which pertain to that passion: so that a man who is full of sorrow does not easily think of great and joyful things, but only of sad things, unless by a great effort he turn his thoughts away from sadness.

[39673] IIª-IIae q. 20 a. 4 ad 3 Ad tertium dicendum quod ipsa etiam negligentia considerandi divina beneficia ex acedia provenit. Homo enim affectus aliqua passione praecipue illa cogitat quae ad illam pertinent passionem. Unde homo in tristitiis constitutus non de facili aliqua magna et iucunda cogitat, sed solum tristia, nisi per magnum conatum se avertat a tristibus.

________________________________________

Ad quartum sic proceditur. Videtur quod desperatio ex acedia non oriatur. Idem enim non procedit ex diversis causis. Desperatio autem futuri saeculi procedit ex luxuria; ut dicit Gregorius, XXXI Moral. Non ergo procedit ex acedia.
[39667] IIª-IIae q. 20 a. 4 arg. 2 Praeterea, sicut spei opponitur desperatio, ita gaudio spirituali opponitur acedia. Sed gaudium spirituale procedit ex spe, secundum illud Rom. XII, spe gaudentes. Ergo acedia procedit ex desperatione, et non e converso.
[39668] IIª-IIae q. 20 a. 4 arg. 3 Praeterea, contrariorum contrariae sunt causae. Sed spes, cui opponitur desperatio, videtur procedere ex consideratione divinorum beneficiorum, et maxime ex consideratione incarnationis, dicit enim Augustinus, XII de Trin., nihil tam necessarium fuit ad erigendum spem nostram quam ut demonstraretur nobis quantum nos Deus diligeret. Quid vero huius rei isto indicio manifestius, quam quod Dei filius naturae nostrae dignatus est inire consortium? Ergo desperatio magis procedit ex negligentia huius considerationis quam ex acedia.
[39669] IIª-IIae q. 20 a. 4 s. c. Sed contra est quod Gregorius, XXXI Moral., desperationem enumerat inter ea quae procedunt ex acedia.
[39670] IIª-IIae q. 20 a. 4 co. Respondeo dicendum quod, sicut supra dictum est, obiectum spei est bonum arduum possibile vel per se vel per alium. Dupliciter ergo potest in aliquo spes deficere de beatitudine obtinenda, uno modo, quia non reputat eam ut bonum arduum One can fail in hope by not deeming it to be an arduous good? does he mean fail as a technical term or in the deficient sense? because this would seem to belong to 'sanguine' ppl... although 'sanguine' may be hopeful it can include the unvirtuously 'hopeful'; alio modo, quia non reputat eam ut possibilem adipisci vel per se vel per alium. This is the failure in hope that we are concerned with here. Ad hoc autem quod bona spiritualia non sapiunt nobis quasi bona, To this that spiritual goods do not taste as though they were good to us, vel non videantur nobis magna bona, or they do not seem to be a great good praecipue perducimur per hoc quod affectus noster est infectus amore delectationum chiefly we are led through this that our "affect" is "infected" by the love of corporeal pleasures, among which chiefly are sexual delights, from which affect for these delights it happens that the human being has a distaste for spiritual goods, and does not hope for them as though for arduous goods. corporalium, inter quas praecipuae sunt delectationes venereae, nam ex affectu harum delectationum contingit quod homo fastidit bona spiritualia, et non sperat ea quasi quaedam bona ardua. Et secundum hoc desperatio causatur ex luxuria. And in this way despair is caused by luxury. Ad hoc autem quod aliquod bonum arduum non aestimet ut possibile sibi adipisci per se vel per alium, perducitur ex nimia deiectione; And when it happens that he does not estimate some arudous good to be possible for himself to achieve through himself or through another, he is led to this by too much dejection, which when it rules the affect of the human being, seems to him that he can never be relieved by some good. quae quando in affectu hominis dominatur, videtur ei quod nunquam possit ad aliquod bonum relevari. Et quia acedia est tristitia quaedam deiectiva spiritus, ideo per hunc modum desperatio ex acedia generatur. And because acedia is a certain sadness that is a dejection of the spirit, so through this way despair is generated by acedia. Hoc autem est proprium obiectum spei, scilicet quod sit possibile, nam bonum et arduum etiam ad alias passiones pertinent. And thus is the proper object of hope, that something be possible, for the good and the difficult pertain also to other passions. POSSIBILITY MAKES HOPE UNIQUE!!!!!! potentiality - the passion of potentiality as oriented towards perfection. Unde specialius oritur ex acedia. Whence it more specially arises from acedia. Potest tamen oriri ex luxuria, ratione iam dicta. Nevertheless it can arise from luxury, for the reasons said above. So luxury and acedia are not equivalent causes - or even necessarily entwined, but they both enter insofar as the question regards - is acedia the cause of despair.
[39671] IIª-IIae q. 20 a. 4 ad 1 Unde patet responsio ad primum.
[39672] IIª-IIae q. 20 a. 4 ad 2 Ad secundum dicendum quod, sicut philosophus dicit, in II Rhetor., sicut spes facit delectationem, ita etiam homines in delectationibus existentes efficiuntur maioris spei. Et per hunc etiam modum homines in tristitiis existentes facilius in desperationem incidunt, secundum illud II ad Cor. II, ne maiori tristitia absorbeatur qui eiusmodi est. Sed tamen quia spei obiectum est bonum, in quod naturaliter tendit appetitus, non autem refugit ab eo naturaliter, sed solum propter aliquod impedimentum superveniens; ideo directius quidem ex spe oritur gaudium, desperatio autem e converso ex tristitia.
[39673] IIª-IIae q. 20 a. 4 ad 3 Ad tertium dicendum quod ipsa etiam negligentia considerandi divina beneficia ex acedia provenit. Homo enim affectus aliqua passione praecipue illa cogitat quae ad illam pertinent passionem. Unde homo in tristitiis constitutus non de facili aliqua magna et iucunda cogitat, sed solum tristia, nisi per magnum conatum se avertat a tristibus.