The Adornment of the Spiritual Marriage, by Jan van Ruysbroeck, , at sacred-texts.com
Out of this generosity there spring a supernatural zeal and diligence in all virtues and all that is seemly. And none can feel this zeal save him who overflows with generosity. It is an inward restless striving after every virtue, after the likeness of Christ and of all His saints. In this zeal a man longs to devote his heart and his senses, his soul and his body, and all that he is, and all that he has and all toward which he aspires, to the glory and praise of God.
This zeal makes a man grow in reason and prudence, and practise the virtues, both of soul and of body, in righteousness. Through this supernatural zeal all the powers of the soul are laid open to God, and are made ready for all virtues. And the conscience rejoices, and the grace of God is increased; the virtues are practised with joy and gladness, and the outward works are adorned.
Whosoever has received this living zeal from God has cast out the fifth mortal sin, which is indolence of the mind or Sloth, as regards the virtues which it is needful that we should practise. And sometimes, this living zeal also casts out the sloth and indolence of the natural body. Of all such Christ says: Blessed are they which do hunger and thirst after righteousness: for they shall be filled, and this shall come to pass when the glory of God shall be manifest to them, and shall fill them, each according to his love and righteousness.