By mystically, the mother and brother of Jesus means the synagogue, (from which according to the flesh He sprung,) and the Jewish people who, while the Saviour is teaching within, come to Him, and are not able to enter, because they cannot understand spiritual things.
But the crowd eagerly enter, because when the Jews delayed, the Gentiles flocked to Christ; but His kindred, who stand without wishing to see the Lord, are the Jews who obstinately remained without, guarding the letter, and would rather compel the Lord to go forth to them to teach carnal things, than consent to enter in to learn spiritual things of Him.
If therefore not even His parents when standing without are acknowledged, how shall we be acknowledged, if we stand without? [ed. note: see Ambr. in Luc., 6, 37] For the word is within and the light within.
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).