Luke 19:42

He here declares that His coming was to bring peace to the whole world. For unto this He came, that He should preach both to them that were near, and those that were afar off. But as they did not wish to receive the peace that was announced to them, it was hid from them.

If thou hadst known, even thou. The Jews were not worthy to receive the divinely inspired Scriptures, which relate the mystery of Christ. For as often as Moses is read, a veil overshadows their heart that they should not see what has been accomplished in Christ, who being the truth puts to flight the shadow. And because they regarded not the truth, they rendered themselves unworthy of the salvation which flows from Christ.

(Hom. 39. in Ev.) The merciful Redeemer wept then over the fall of the false city, which that city itself knew not was about to come upon it. As it is added, saying, If thou hadst known, even thou (we may here understand) wouldest weep. Thou who now rejoicest, for thou knowest not what is at hand. It follows, at least in this thy day. For when she gave herself up to carnal pleasures, she had the things which in her day might be her peace. But why she had present goods for her peace, is explained by what follows, But now they are hidden from thy eyes. For if the eyes of her heart had not been hidden from the future evils which were hanging over her, she would not have been joyful in the prosperity of the present. Therefore He shortly added the punishment which was near at hand, saying, For the days shall come upon thee.

(Hom. 39. in Ev.) For our Redeemer does not cease to weep through His elect whenever he perceives any to have departed from a good life to follow evil ways. Who if they had known their own damnation, hanging over them, would together with the elect shed tears over themselves. But the corrupt soul here has its day, rejoicing in the passing time; to whom things present are its peace, seeing that it takes delight in that which is temporal. It shuns the foresight of the future which may disturb its present mirth; and hence it follows, But now are they hid from thine eyes.