Imitation of Christ

Multum proinde proficies, si te seriatum ab omni temporali cura conserves. Valde deficies, si aliquid temporale reputaveris. Nihil altum, nihil magnum, nihil gratum, nihil acceptum tibi sit, nisi pure Deus, aut de Deo sit. Totum vanum exstima, quidquid consolationis occurrit de aliqua creatura. Amans Deum anima sub Deo contemnit, despicit universa. Solus Deus æternus et immensus, implens omnia, solatium est animæ et vera mentis lætitia.

Then you will make great progress if you keep yourself free from all temporal care. You will lamentably fall away if you set a value upon any worldly thing. Let nothing be great, nothing high, nothing pleasing, nothing acceptable unto you, save God Himself or the things of God. Reckon as altogether vain whatsoever consolation comes to you from a creature. The soul that loves God looks not to anything that is beneath God. God alone is eternal and incomprehensible, filling all things, the solace of the soul, and the true joy of the heart. 

Imitation of Christ, II, 5:3