The following excerpt is taken from St. Francis de Sales' book, On the Love of God.
Why do hounds, think you, Theotimus, more ordinarily lose the scent or strain of their quarry in the spring-time than at other times?
It is, as hunters and philosophers say, because the grass and flowers are then in their vigour, so that the variety of smells which they send out so fills the hounds' sense of smelling that they can neither take nor follow the scent of their game, among so many scents which the earth exhales.
In sooth those souls that ever abound in desires, designs and projects, never desire holy celestial love as they ought, nor can perceive the delightful strain and scent of the divine beloved, who is compared to the roe, and to the little fawn of the doe.
Lilies have no season, but flower soon or late, as they are deeper or less deep set in the ground: for if they be thrust three fingers only into the earth they will presently blossom, but if they be put six or nine, they come up proportionately later. If the heart that aims after Divine love be deeply engaged in terrene and temporal affairs, it will bud late and with difficulty; but if it have only so much to do with the world as its condition requires, you shall see it bloom timely in love, and send out a delicious odour.
For this cause the Saints betook themselves to deserts, that being freed from worldly cares they might more ardently apply to heavenly love. For this the spouse shut one of her eyes, to the end that she might keep the sight of the other alone more fixedly, and thereby take better aim at the very midst of her beloved's heart, which she desires to wound with love. And for this same reason she keeps her hair so plaited and gathered up in a tress that she seems to have one only hair which she makes use of as a chain, to bind and bear away her spouse's heart, whom she makes a slave to her love.
They who desire for good and all to love God, shut up their understanding from discoursing of worldly things, to employ it more earnestly in the meditation of divine things, and gather up all their pretensions under the sole intention which they have of loving only God. Whosoever desires something which he desires not for God that much less desires God.
A religious man demanded of the Blessed Giles what he could do most grateful to God; and he answered him by singing: "One to one, one to one;" that is, one only soul to one only God. So many desires and loves in a heart are like many children at one breast, who, as they cannot all suck at once, struggle each one for his turn, so that at last the fount dries up. He who aspires to heavenly love, must sedulously reserve for it his leisure, his spirit and his affections.