Treasure, which one?
According to the Gospel, to store up treasures on earth, literally, treasurising on earth, is extremely dangerous. Why? First of all because it is a kind of wealth-energy that wears out, and what wears out can be stolen or burglarized; it is not God's, it does not come from God but from someone else. So treasurizing on earth earthly treasures, consuming vital energies, letting our health go to ruin, ignoring our friends/families, our serenity and peace, anxiously and violently commiting ourselves to despoiling our brothers in order to accumulate wealth and things that wear out and or can inevitably be stolen because they do not come from God and do not lead to God is not only dangerous but also stupid. If the eye of our mind and spirit is so stupid and short-sided, the text uses the word bad, that it see earthly treasures as important and necessary, our heart will work hard trying to treasurise that kind of useless, unusable treasures. If the eye of our mind and spirit is so simple and clean that it sees the wealth of the heavenly kingdom as very important, our heart will keep busy trying to treasurise that kind of treasure that is useful now, usable forever, and which nothing or no one will ever be able to take away from us.
A note with regard to the Greek text: in verses 22 and 23 the text says literally: the lamp of the body is the eye, if thus your eye is clear, your entire body will be luminous: if instead your eye is bad, your entire body will be dark. Jesus establishes a connection between the quality and the type of eyesight and the state of the body, of the physical being. Clear eye, luminous body: bad eye, dark body. Jesus reveals an interdependency, a link, an unbreakable bond between the quality of spiritual eyesight and health, harmony, and the body's quality of life. According to the Gospel, the treasure which the heart chooses has a direct and inseparable connection with the health and harmony of the physical state. The heart's treasure leads to a person's light or darkness, life or death.