Now we declare that Virginity is man's “fellow-worker” and helper in achieving the aim of this lofty passion. In other sciences men have devised certain practical methods for cultivating the particular subject; and so, I take it, virginity is the practical method in the science of the Divine life, furnishing men with the power of assimilating themselves with spiritual natures. The constant endeavour in such a course is to prevent the nobility of the soul from being lowered by those sensual outbreaks, in which the mind no longer maintains its heavenly thoughts and upward gaze, but sinks down to the emotions belonging to the flesh and blood.
How can the soul which is riveted to the pleasures of the flesh and busied with merely human longings turn a disengaged eye upon its kindred intellectual light? This evil, ignorant, and prejudiced bias towards material things will prevent it. The eyes of swine, turning naturally downward, have no glimpse of the wonders of the sky; no more can the soul whose body drags it down look any longer upon the beauty above; it must pore perforce upon things which though natural are low and animal.
To look with a free devoted gaze upon heavenly delights, the soul will turn itself from earth; it will not even partake of the recognized indulgences of the secular life; it will transfer all its powers of affection from material objects to the intellectual contemplation of immaterial beauty. Virginity of the body is devised to further such a disposition of the soul; it aims at creating in it a complete forgetfulness of natural emotions; it would prevent the necessity of ever descending to the call of fleshly needs.
Once freed from such, the soul runs no risk of becoming, through a growing habit of indulging in that which seems to a certain extent conceded by nature's law, inattentive and ignorant of Divine and undefiled delights. Purity of the heart, that master of our lives, alone can capture them.
Source: On Virginity (New Advent)