The Pure In Heart

Beati mundo corde, quoniam Deum ipsi videbunt. Mundis corde conspectum Dei spondet. Nihil enim pollutum et sordidum ad occursum divinae claritatis insistit, et ad conspectum Dei acies obsoletae mentis hebetatur: eos scilicet et visui et occursui Dei esse patentes, quibus per animi nitorem ac vitae puritatem potestas sit contuendi. Non enim nisi spiritus perfecti, et immortalitate immutati, quod solis mundis corde dispositum est, hoc quod in Deo est immortale cernemus. In Evangelium Matthaei Commentarius, Sanctus Hilarius Pictaviensis

Blessed are the pure in heart, for they shall see God. 1 He promises the vision of God to those who are pure in heart. So nothing polluted or filthy may disrupt the meeting with the Divine Splendor and forgetfulness of the acuity of the mind is dulled for the vision of God, that is to say, for those who endure for the vision and encounter with God, by which, through the brightness of the soul and purity of life, comes the ability to behold it. Certainly it cannot be without perfection of spirit and transformation into immortality, for it is only for those pure in heart to see that which is immortal in God. Saint Hilary of Poitiers, from the Commentary On The Gospel of Saint Matthew 1 Mt 5.8