In general terms we all discern, that is to say we all have to choose between and evil. But the discernment as spiritual gift is something else.
The gift of discernment is one of the seven spiritual gifts of the holy spirit that define the human integrity. Remember that the spiritual gifts are perfect virtues, or complete virtues, virtues that cannot be improve or surpassed in their own genre.
Thomas Aquinas makes a distintion between perfect virtues of the will, like the mercy, piety, gift of fortitude (continuous improvement), and the spiritual gifts of knowledge like the discernment, the wisdom and the knowledge.
The discernment is related with the Gnosis. In the Gnosis we receive the essence of God, the wisdom, manteining the substance.
To explain it better: the essence is the main characteristic of something. The essence of god is the wisdom, the essence of man is reason. The essence is the immaterial substance. The substance is that of which it is predicated. The substance of man is the person, the substance of God is wisdom. The substance has to do with the physical or with the physical description of the objects, a person is an animal with two arms and two legs, who has the abbility to speak and comunicate.
The Gnosis change the essence of man, the reason is change in wisdom , manteining the substance without modifications (the person remain the same). This is why we receive the seven gifts.
We have an example of Gnosis in the Bible
King Solomon meets God in a dream, and God grants him a wish, Salomon asks God how to listen.
That is to say discernment arises from listening: perceive with attention (listening), meditate with intuition and inspiration, decide with discernment.
The discernment as spiritual gift is the adequate capacity to separate good from evil. The good discernment search the truth, is the precise and the exact, is progressive, is way, and improves the life. The good discernment is free from error.
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