He "who does not resolve the doubt" he "instills" is a false prophet

     "We find some people who study philosophy and say some things that are not true according to the faith.  And when someone tells them that this is opposed to the faith, they answer that the Philosopher says this, but that they themselves do not maintain this; yes, that they only repeat the words of the Philosopher.  Such is a false prophet, or a false teacher, because causing doubt and not solving it is the same as giving way to it.  This is signified in Ex 21:33-34, where it says that 'if someone digs a pit and opens the cistern without covering it over,' and a cow belonging to his neighbor comes and falls into the cistern, he who left the cistern open is bound to pay him restitution.  Someone who causes doubt about these things that regard the faith, opens the cistern.  Someone who does not solve the doubt, although he has a sound and bright intellect and is not deceived, is the one who does not cover over the cistern.  Still, someone else, who does not have such a bright intellect, may well be deceived, and then the one who causes the doubt is bound to restitution, since because of him that person fell into the pit."

     St. Thomas Aquinas, Sermon 14 on the Attendite a falsis prophetis (Mt 7:15-16) 2.1.2.1 (22), 26 July 1271, trans. Mark-Robin Hoogland, C.P. (Thomas Aquinas:  the academic sermons, FCMC 11 (Washington, DC:  The Catholic University of America Press, 2010), 292).  Trans. Athanasius Sulavik:

"others, who study philosophy and advance some things which are not true according to the faith, who when told that this is repugnant to the faith, respond by saying that they themselves do not assert this, but rather they are only repeating the words of the Philosopher. Such a person is a false prophet or a false teacher, for it is the same thing to instill doubt and not to resolve it, as it is to affirm the doubt. This point is illustrated in Exodus where it says that if anyone digs a well and opens the pit and does not cover it, and if their neighbor's ox comes along and falls into the pit, the person who opened the pit is held accountable for its restitution. That person who instills doubt about those things which belong to faith opens a pit; he does not cover the pit who does not resolve the doubt, even though he himself possesses sound and clear understanding and is not deceived. Nonetheless the other person who does not possess such clear understanding is truly deceived, and so that man who instilled the doubt is held accountable for restitution, since it was through him that the other man fell into the pit."

Latin from Sulavik:

"aliqui qui student in philosophia, et dicunt aliqua quae non sunt vera secundum fidem; et cum dicitur eis quod hoc repugnat fidei, dicunt quod philosophus dicit hoc, sed ipsi non asserunt: imo solum recitant verba philosophi. Talis est falsus propheta, sive falsus doctor, quia idem est dubitationem movere et eam non solvere quod eam concedere; quod signatur in Exod. 21, 33, 34, ubi dicitur quod si aliquis foderit puteum, et aperuerit cisternam, et non cooperuerit eam, veniat bos vicini sui, et cadat in cisternam, ille qui aperuerit cisternam teneatur ad ejus restitutionem. Ille cisternam aperuit, qui dubitationem movet de his quae faciunt ad fidem. Cisternam non cooperit, qui dubitationem non solvit, etsi habeat intellectum sanum et limpidum, et non decipiatur. Alter tamen qui intellectum non habet ita limpidum bene decipitur, et ille qui dubitationem movit tenetur ad restitutionem, quia per eum ille cecidit in foveam."

Latin from Corpus Thomisticum.

Trust the saints on what you haven't yourself experienced

"Although the tri-hypostatic nature of the Godhead—that is in no way destroyed by the principle of unity—was in later times revealed to the ends of the earth, it was also fully known to the prophets prior to the fulfillment of the things prophesied and was readily accepted by those who trusted in them.  In the same manner, even at this present time we are not ignorant of the doctrines of the Christian confession, both those which are openly proclaimed and those which are mystically and prophetically revealed by the Spirit to such as are accounted worthy.  These are persons who have been initiated by actual experience, who have renounced possessions, human glory and the ugly pleasures of the body for the sake of the evangelical life; and not only this, but they have also strengthened their renunciation by submitting themselves to those who have attained spiritual maturity in Christ.  Through the practice of the life of stillness they devote their attention undistractedly to themselves and to God, and by transcending themselves through sincere prayer and by establishing themselves in God through their mystical and supra-intellectual union with Him they have been initiated into what surpasses the intellect.  Others again have learnt about these things through their reverence, faith and love for such persons.

"If, then, anyone condemns as Messalians those who declare this deifying grace of God to be uncreated, ungenerated and completely real, and calls them ditheists, he must know . . . that he is an adversary of the saints of God. . . .  But if anyone believes, is persuaded by and concurs with the saints and does not 'make excuses to justify sin' [(Ps 141:4 LXX)], and if although ignorant of the manner of the mystery he does not because of his ignorance reject what is clearly proclaimed, let him not refuse to enquire and learn from those who do possess knowledge."

     Gregory of Palamas, “Declaration of the Holy Mountain in defence of those who devoutly practice a life of stillness” Prologue and 1 (=Triads I.ii?), in Philokalia:  the complete text, translated from the Greek and edited by G. E. H. Palmer, Philip Sherrard, and Kallistos Ware, vol. 4 (London:  Faber & Faber, 1995), 418-420.

"the twofold perfection which is required of the student of [the science of mystical theology]"

     "The sort of people to whom this kind of teaching ['which is entitled Mystical Theology'] is meant to be addressed is alluded to in the word 'Israel,' which means 'very straight' and 'a man who sees God.'  This reveals the twofold perfection which is required of the student of this science:  clarity of understanding in order to see God and right behavior in practice, which is how we come to such clarity or sharpness of understanding [(limpiditas ad videndum Deum, et rectitudo operis, per quam ad dictam limpiditatem vel acumen devenitur)]."

     St. Albert the Great, Commentary on Dionysius' Mystical theology, chap. 1 (Albert & Thomas:  selected writings, translated, edited, and introduced by Simon Tugwell, O.P. (New York, NY, and Mahwah, NJ:  Paulist Press, 1988), 135).  I was put onto this by Fr. Bernhard Blankenhorn, O.P., who quotes it at the beginning of his lecture "Albertus Magnus on contemplative ascent to God," Renewing Mystical Theology: The Link Between Theological Doctrine and Spiritual Practice in Medieval Spiritualities, Thomistic Institute, Angelicum, Rome, 26 February 2021.  Fr. Blankenhorn's concluding comments are eminently quote-worthy as well.  Latin from p. 812 of vol. 14 of the Borgnet edition of 1892, i.e not vol. 37.2 of the Editio Coloniensis.