Ultimo fine non est utendum quia uti importat applicationem alicuius ad aliquid; quod autem applicatur ad aliud, se habet in ratione eius quod est ad finem, et ideo uti semper est eius quod est ad finem.
We cannot use the last end because use implies the application of one thing to another; and that which is applied to another has its formal aspect as a means to an end, and consequently use always regards the means.
Finis assumitur in facultatem voluntatis, ut voluntas in illo quiescat. Unde ipsa requies in fine, quae fruitio est, dicitur hoc modo usus finis. Sed id quod est ad finem, assumitur in facultatem voluntatis, non solum in ordine ad usum eius quod est ad finem, sed in ordine ad aliam rem, in qua voluntas quiescit.
The end is applied to the purpose of the will, that the will may find rest in it. Consequently this rest in the end, which is the enjoyment thereof, is in this sense called use of the end. But the means are applied to the will's purpose, not only in being related for use as means, but as ordained to something else in which the will finds rest.
Dicit Augustinus, in libro octoginta trium quaest., "Deo nullus recte utitur, sed fruitur".
Augustine says (QQ. 83, qu. 30): "No one rightly uses God, but one enjoys Him."