The Adornment of the Spiritual Marriage, by Jan van Ruysbroeck, , at sacred-texts.com
Now mark how, in each of our works, we shall go out to meet God, and shall increase our likeness unto Him, and shall more nobly possess the fruitive unity. By every good work, how small soever it be, which is directed to God with love and with an upright and single intention, we earn a greater likeness, and eternal life in God. A single intention draws together the scattered powers into the unity of the spirit, and joins the spirit to God. A single intention is end, and beginning, and adornment, of all virtues. A single intention offers to God praise and honour and all virtues: and it pierces and passes through itself, and all the heavens, and all things, and finds God within the simple ground of its own being. That intention is single which aims only at God and in all things only at their connection with God. The single intention casts out hypocrisy and duplicity, and a man must possess it and practise it in all his works above all other things; for it is this which keeps man in the presence of God, clear in understanding, diligent in virtue, and free from outward fear, both now and in the Day of Doom. Singleness of intention is the single eye of which Christ speaks, giving light to the whole body—that is, to the man's works and his whole life and cleansing it of sin. Singleness of intention is the inward, enlightened, and loving tendency of the spirit; it is the foundation of all ghostliness; it includes in itself faith, hope, and charity, for it trusts in God and is faithful to Him. It casts nature underfoot, it establishes peace, it drives out ghostly discontent, and preserves fulness of life in all the virtues. And it gives peace and hope and boldness toward God, both now and in the Day of Doom.
Thus we shall dwell in the unity of the spirit, in grace and in likeness; and shall always go out to meet God by means of the virtues, and offer up to Him with a simple intention our whole life and all our works; and thus in every work, and ever more and more, we shall increase our likeness. And thus we rise up out of the ground of our single intention, and pass through ourselves and go out to meet God without means, and rest in Him in the abyss of simplicity: there we possess that heritage which has been prepared for us from all eternity. All ghostly life and all works of virtue consist in the Divine likeness and in singleness of intention; and all their supreme rest consists in simplicity above all likeness. Nevertheless, one spirit surpasses another in virtue and in likeness, and each possess its own proper being in itself, according to the degree of its nobleness. And God suffices each one in particular, and each one, according to the measure of his love, seeks God in the ground of his spirit; both here and in eternity.