Whoever has a correct knowledge of himself, also has a correct knowledge of the creatures which God brought [into being] out of nothing; he likewise knows the dignity of the noetic and immortal human spirit, confined for a time in a body of clay, so that in it he would perfect himself in the virtues. And whoever knows this, knows that one must love God; and whoever loves God, loves everyone.
Saint Anthony the Great
An understanding of one's nature curtails the soul's haughtiness, drives all pride and arrogance out of it; in a word, it makes a man a disciple of the Lord.
Saint Basil the Great
He who does not know himself cannot know anything else either. But he who knows himself, through this itself, will also succeed in all the other virtues.
Saint John Chrysostom
How can we know ourselves? The image of the eye, seen in a mirror, is taken from the eye itself and is its imprint; but with regard to the character and image of the soul it is the other way round: the form the image of the soul is traced, is taken from the Divine beauty; consequently, the soul only contemplates itself when it sees itself in its prototype, which is God.
Saint Gregory of Nyssa
He who perceives his sins is higher then he who raises the dead by his prayer; he who has been vouchsafed to see himself is better than he who has been vouchsafed to see angles.
St. Isaac the Syrian
Whoever has come to know himself will never give himself up to deception and will not undertake what is beyond him.
St. John Climacus
Many want to know what is happening in foreign countries, while they do not seek what is to be found in their own soul.
Hierarch Tikhon of Zadonsk
Test thyself, who thou art; come to know thy nature; come to know that thy body is mortal, while thy soul is immortal, that our life is twosided: one side, proper the flesh, is transitory, while the other, related to the soul, does not admit limitation. Therefore, take heed to thyself, do not dwell on the mortal as eternal, and do not disdain the eternal as transitory. Do not care about the flesh, because it passes away; take care for the soul, a thing immortal.
Saint Basil the Great
When walking in a forest, in a garden or in a meadow, and on seeing the young shoots of the plants, the fruits on the trees and the variety of the field flowers, take for thyself a lesson from all this vegetation of God's, namely such a lesson: every sapling unfailingly gives considerable new growth in the summer, unfailingly grows in size and height it is as if with each year every tree is endeavoring to move forward by the power granted to it by God. Thus, say to thyself: I, too, with each day, with each year must unfailingly grow morally higher and higher, better and better, more and more perfect; I must move forward on the path to the Kingdom of Heaven, or to the Heavenly Father, by the power of the Lord Jesus Christ and His Spirit, Which lives and acts in me.
Holy righteous John of Kronstadt