Ps 145:4

“There are many uses of the word spirit in general in the sacred Scriptures, and a person could easily become confused from ignorance, if he did not know to what sort of spirit the particular text refers. Therefore, we must be sure of the nature of the Holy Spirit according to Scripture. For example Aaron is called Christ (anointed), and David also, and Saul and others are called Christs, yet there is only one true Christ; similarly since the name of spirit has been given to many things, we must determine what in particular is called the Holy Spirit. Many things are called spirits; our soul is called spirit; this wind that is blowing is called spirit; great valor is called spirit; impure action is called spirit; and a hostile devil is called spirit. Take care, therefore, when you hear such things, not to mistake one for another because of the similarity of name. Scripture says of the soul, "When his spirit departs he returns to the earth"; and again of the soul, "Who forms the spirit of a person within him." It says in the Psalms of the angels, "Who make your angels spirits";16 it says of the wind: "With a vehement spirit you shall break in pieces the ships of Tharsis"; and "As the trees of the woods are moved with the spirit";18 and "Fire, hail, snow, ice, spirit of storm." Our Lord says of his blessed teaching: "The words that I have spoken to you are spirit and life," that is, they are spiritual. The Holy Spirit is not an utterance of the tongue; he is living, granting wise speech, speaking and discoursing himself.”

“"His breath shall go forth, and he shall return to his earth: in that day shall all his thoughts perish" (ver. 4). Where is swelling? where is pride? where is boasting? But perhaps he will have passed to a good place, if indeed he have passed. For I know not whither he who spake thus hath passed. For he spake in pride; and I know not whither such men pass, save that I look into another Psalm, and see that their passage is an evil one. "I beheld the wicked lifted up above the cedars of Libanus, and I passed by, and, lo, he was not; and I sought him, and his place was not found." The good man, who passed by, and found not the wicked, reached a place where the wicked is not. Wherefore, brethren, let us all listen: brethren, beloved of God, let us all listen; in whatsoever tribulation, in whatsoever longing for the heavenly gift, "let us not trust in princes, nor in sons of men, in whom is no salvation." All this is mortal, fleeting, perishable.”

“The Apostle says, "I am afraid that just as the serpent deceived Eve with his cunning, so your minds may be corrupted from the chastity which is in Christ." But their minds are corrupted by such conversations: "Let us eat and drink, for tomorrow we die." Those who love these things, who pursue these things, who consider this life alone to be, who hope for nothing beyond, who either do not pray to God or pray to Him for these very things, for whom the discourse of diligence is burdensome, let them hear us say these things with great sadness. They want to eat and drink; for tomorrow they die. If only they truly thought that they would die tomorrow. For who is so mad and perverse, who is so much an enemy of his own soul, who, dying tomorrow, does not think that all things for which he labors will have ended? For it is written: "On that day all his thoughts will perish." Even if men take care in drawing up a will on the imminent day of their death for the sake of those they leave behind, how much more should they think of their own soul? Man considers whom he will leave behind, but he does not think of himself who leaves all these things behind.”

“"[His spirit] shall leave]" - That [spirit] which dwells in his heart. "He shall return to his earth" - For the bones are, in their structure, of earth, and they are the foundations of the body. The meaning of the word "עשתונותיו" is "his thoughts", like [it says in Yonah 1:6]: "Perhaps God will think (יתעשת) [of us and we will not be lost]." [this being] like saying "God will think, will think of me."”

“תצא רוחו. "His breath goes forth": And how can a person have salvation if he does not have control over his spirit to preserve it? For his spirit may depart suddenly, and he returns to his earth. Whatever he plans to do, he will not be able to accomplish, for once his sustaining spirit departs, on the day of his death, his thoughts perish.”