Keep thyself pure. 1 Timothy 5:22.
To know what constitutes purity of mind, soul, and body is an important part of education.
When the character is lacking in purity, when sin has become a part of the character, it has a bewitching power that is equal to the intoxicating glass of liquor. The power of self-control and reason is overborne by practices that defile the whole being; and if these sinful practices are continued, the brain is enfeebled and diseased, and loses its balance. Such ones are a curse to themselves and to all who have any connection with them….
Bad habits are more easily formed than good habits, and the bad habits are given up with more difficulty. The natural depravity of the heart accounts for this well-known fact—that it takes far less labor to demoralize the youth, to corrupt their ideas of moral and religious character, than to engraft upon their character the enduring, pure, and uncorrupted habits of righteousness and truth. Self-indulgence, love of pleasure, enmity, pride, self-esteem, envy, jealousy, will grow spontaneously, without example and teaching. In our present fallen state all that is needed is to give up the mind and character to its natural tendencies. In the natural world, give up a field to itself and you will see it covered with briers and thorns; but if it yields precious grain or beautiful flowers, care and unremitting labor must be applied.
Now we present before you the necessity of constant resistance to evil. All heaven is interested in men and women whom God has valued so much as to give His beloved Son to die to redeem them. No other creature that God has made is capable of such improvement, such refinement, such nobility as man. Then when men become blunted by their own debasing passions, sunken in vice, what a specimen for God to look upon! Man cannot conceive what he may be and what he may become. Through the grace of Christ he is capable of constant mental progress. Let the light of truth shine into his mind and the love of God be shed abroad in his heart and he may, through the grace Christ has died to impart to him, be a man of power—a child of earth but an heir of immortality.
From “Maranatha”, by Ellen White