nothing

To be humble let us listen to the revelation of the Holy Ghost which is infallible. "Behold you are nothing, and your work is of that which hath no being." [Isa. xli, 24] But who is really convinced of his own nothingness?
It is for this reason that in holy Scripture it is said: "Every man is a liar." [Ps. cxv, 2] For there is no man who from time to time does not entertain some incredible self-esteem, and form some false opinion as to his being, or having, or achieving something more than is possible to his own nothingness.
To know what our body is in reality, it will suffice for us to look into the grave, for, from what we see there, we must inevitably conclude that as it is with those decayed bodies, so it will soon be with us. And with this reflection I must say to myself: "Why is earth and ashes proud?" [Ecclus x, 9] "Behold the glory of man! for his glory is dung and worms; today he is lifted up, and tomorrow he shall not be found, because he is returned into his earth, and his thought is come to nothing." [1 Mach. ii, 62, 63]
O my soul, without going further to seek truth, enter in thought into the heart of thy dwelling which is thy body! "Go in and shut thyself up in the midst of thy house." [Ezek. iii, 24] Go in and look well around thee, and thou shalt find nothing but corruption. "Go into the clay and tread." [Nahum iii, 14] Wherever thou turnest thou wilt see nothing but putrefaction oozing forth.

rob God

When we consider well what we are in body, and what we are in soul, it seems to me most easy to humble oneself, and even most difficult to be proud. To be humble it suffices that I should nourish within myself that right feeling which belongs to every man who is honorable in the eyes of the world, to be content with one's own without unjustly depriving our neighbor of what is his. Therefore, as I have nothing of my own but my own nothingness, it is sufficient for humility that I should be content with this nothingness. But if I am proud, I become like a thief, appropriating to myself that which is not mine but God's. And most assuredly it is a greater sin to rob God of that which belongs to God than to rob man of that which is man's.

no excuse

6. There is no valid excuse for not being humble, because we have always, within and without, abundant reasons for humility: "And thy humiliation shall be in the midst of thee." It is the Holy Ghost who sends us this warning by the mouth of His prophet Micheas." [vi, 14]

know myself

How and when do I practice its acts, acknowledging and confessing my unworthiness before God? The following was the frequent prayer of St. Augustine, "Noscam Te, noscam me-----May I know Thee; may I know myself!" and by this prayer he asked for humility, which is nothing else but a true knowledge of God and of oneself. To confess that God is what He is, the Omnipotent, "Great is the Lord, and exceedingly to be praised," [Ps. xlvii, 1] and to declare that we are but nothingness before Him: "My substance is as nothing before Thee" [Ps. xxxviii, 6]-----this is to be humble.

Heaven

No one can deny this truth, that humility is essential to all those who wish to be saved. "No one reaches the kingdom of Heaven except by humility," says St. Augustine. [Lib. de Salut. cap. xxxii]

precept

5. There is a kind of humility which is of counsel and of perfection such as that which desires and seeks the contempt of others; but there is also a humility which is of necessity and of precept, without which, says Christ, we cannot enter into the kingdom of Heaven: "Thou shalt not enter into the kingdom of Heaven." [Matt. xviii, 3] And this consists in not esteeming ourselves and in not wishing to be esteemed by others above what we really are.

understanding

How shameful it would be for anyone, after studying for many years in a school of art or science, under the teaching of excellent masters, if he were still to remain absolutely ignorant! My shame is great indeed, because I have lived so many years in the school of Jesus Christ, and yet I have learnt nothing of that holy humility which He sought so earnestly to teach me. "Have mercy upon me according to Thy Word. Thou art good, and in Thy goodness teach me Thy justifications. Give me understanding, and I will learn Thy Commandments." [Ps. cxviii, 58, 68, 73]