Impossibile est quod voluntas unius hominis simul se habeat ad diversa, sicut ad ultimos fines, quia potestas voluntatis non habet ut faciat opposita esse simul (quod contingeret, si tenderet in plura disparata sicut in ultimos fines).
It is impossible for one man's will to be directed at the same time to diverse things, as last ends, because the power of the will does not extend to making opposites exist at the same time (which would be the case were it to tend to several diverse objects as last ends).
Etsi plura accipi possint quae ad invicem oppositionem non habeant, tamen bono perfecto opponitur quod sit aliquid de perfectione rei extra ipsum.
Although it is possible to find several things which are not in opposition to one another, yet it is contrary to a thing's perfect good, that anything besides be required for that thing's perfection.
Cum unumquodque appetat suam perfectionem, illud appetit aliquis ut ultimum finem, quod appetit, ut bonum perfectum et completivum sui ipsius. Unde Augustinus dicit, XIX de Civ. Dei, "finem boni nunc dicimus, non quod consumatur ut non sit, sed quod perficiatur ut plenum sit".
Since everything desires its own perfection, a man desires for his ultimate end, that which he desires as his perfect and crowning good. Hence Augustine (De Civ. Dei xix, 1): "In speaking of the end of good we mean now, not that it passes away so as to be no more, but that it is perfected so as to be complete."
Oportet igitur quod ultimus finis ita impleat totum hominis appetitum, quod nihil extra ipsum appetendum relinquatur. Quod esse non potest, si aliquid extraneum ad ipsius perfectionem requiratur. Unde non potest esse quod in duo sic tendat appetitus, ac si utrumque sit bonum perfectum ipsius.
It is therefore necessary for the last end so to fill man's appetite, that nothing is left besides it for man to desire. Which is not possible, if something else be required for his perfection. Consequently it is not possible for the appetite so to tend to two things, as though each were its perfect good.
Sicut omnium hominum est naturaliter unus finis ultimus, ita huius hominis voluntas in uno ultimo fine statuatur.
Just as of all men there is naturally one last end, so the will of an individual man must be fixed on one last end.
Sicut in processu rationis, principium est id quod naturaliter cognoscitur, ita in processu rationalis appetitus, qui est voluntas, oportet esse principium id quod naturaliter desideratur. Hoc autem oportet esse unum, quia natura non tendit nisi ad unum. Principium autem in processu rationalis appetitus est ultimus finis. Unde oportet id in quod tendit voluntas sub ratione ultimi finis, esse unum.
Just as in the process of reasoning, the principle is that which is naturally known, so in the process of the rational appetite, i.e. the will, the principle needs to be that which is naturally desired. Now this must needs be one: since nature tends to one thing only. But the principle in the process of the rational appetite is the last end. Therefore that to which the will tends, under the formal aspect of its last end, is one.