The Adornment of the Spiritual Marriage, by Jan van Ruysbroeck, , at sacred-texts.com
There are some men who are very subtle in words, and skilful in showing forth high things, and yet do not enjoy this enlightened condition, neither this common and generous charity. In order that these men may learn to know themselves, and also may be known of others, I will distinguish them by three signs. By the first sign they may be known of themselves, and by the two others they may be recognised of all men of understanding.
The first sign: Whereas the enlightened man, by virtue of the Divine light, is simple and stable and free from curious considerations, these others are manifold and restless and full of subtle reasonings and reflections, and they do not taste inward unity, nor the satisfaction which is without images. And by this they may know themselves.
The second sign: Whereas the enlightened man possesses a wisdom inpoured by God, wherein he knows and distinguishes the truth without effort, these men have shrewd and sudden notions, with which they work in their imagination, and which they display and develop with much cunning. But their ground is barren and they cannot bring forth fruitful doctrine. Their doctrines are manifold, they are concerned with outward things and addressed to the understanding. And thereby inward men are troubled, hindered, and led astray. They neither lead nor point to unity; but they teach subtle observations in multiplicity. Such people hold obstinately to their own doctrine and opinion, even though another opinion be as good as their own. And they are idle and careless as regards all virtues. Spiritual pride is in all their being. This is the second sign.
The third sign: Whereas the enlightened and loving man flows forth in love towards all in heaven and on earth, as you have heard, this other man sets himself apart in all things. He thinks himself to be the wisest and the best of all; and desires that others should think highly of him and his teaching. All those whom he does not teach and advise, all those who do not follow his way of life and do not cling to him as their master, these seem to him to be sunk in error. He is large and spacious in satisfying his bodily needs, and little faults do not count heavily with him. This man is neither just, nor humble, nor generous, nor a servant of the poor, nor inward, nor fervent, nor does he feel the love of God. He knows neither God, nor his own being, in the way of true virtue. This is the third sign.
Mark these, and study them, and cast them out of yourselves, and out of all men in whom you remark them; but condemn no one for such things unless it be that they have proved it by their deeds, for this would soil your heart and would hinder it in the knowledge of Divine truth.