Jerome: Doubtful Understandings of Enigmatic Statements Don't Establish Doctrines

Jerome (347-420) commenting on Matthew 13:33: They interpret the three measures of wheat this way: while there is not a different nature in each [person of the Trinity], they tend toward a unity of substance. This is a godly interpretation to be sure, but a doubtful understanding of a parable and an enigmatic saying can never advance the authority of dogmas. FC, Vol. 117, St. Jerome: Commentary on Matthew (Washington D.C.: The Catholic University of America Press, 2008), p. 160.
Latin text: Farinae quoque sata tria, dum non est in singulis diversa natura, et ad unitatem trahunt substantiae. Pius quidem sensus, sed numquam parabolae et dubia aenigmatum intelligentia, potest ad auctoritatem dogmatum proficere. Commentariorum in Evangelium Matthaei, Liber Secundus, Caput XIII, v. 33, PL 26:91C.