Ephrem the Syrian : "Instead of the thorn shall come up the cypress; instead of the brier shall come up the myrtle." The spiritual meaning of these words refers to the change of customs, which sprouted and rose up in the advent of Christ among those nations who embraced his faith. Instead of thorns, which represent the sins, and instead of the brier, which is devoid of fruits, the sweet-smelling cypress and the myrtle have risen, which are figures of the actions of virtue, purity and holiness and … are pleasing to God and delight him. — COMMENTARY ON Isaiah 55:13 Gregory the Dialogist : Of the abatement of this heat it is said to her by Isaiah, by promise of the Lord, "Instead of the ground willow shall come up the fir-tree, and instead of the nettle shall come up the myrtle tree." For 'instead of the ground willow there comes up in her the fir-tree,' when in the heart of the Saints, instead of the sunkenness of earthly thought, the elevation of heavenly contemplation rises up. Now the nettle is altogether of a fiery nature. But the myrtle is said to be of cooling virtue, and therefore 'instead of the nettle there comes up the myrtle tree,' when the minds of the righteous are brought from the irritation and heat of bad habits to coolness and quietness of the thoughts, while they now no longer seek earthly things, while they extinguish the flames of the flesh by heavenly aspirations. — Morals on the Book of Job, Book 18, Section 32 Jerome : And as for the nature of proper names, it must be said that evil things are turned into good things, and virtues are born from vices, that is, justice from injustice, fortitude from temerity, temperance from luxury, and prudence from foolishness.… Therefore, what is said in the Gospel: "A good tree cannot bear bad fruit," does not refer at all to the nature of things, as the heretics want it to, but to the choice of the mind. Finally, it is inferred: "Either make a good tree and its fruits good." From this it is clear, each one by their own will makes their soul a good or bad tree, whose fruits are varied. — Commentary on Isaiah Theodoret of Cyrus : He has shown by this the change undergone by the foreign nations. For people who formerly resembled useless and rampant weeds, behold, after having had knowledge of the Savior, they have imitated the height of the cypress and the sweet aroma of the myrtle. They proclaim by their deeds the power of our God and Savior, in offering their own change as a sign [to others] and as a miracle, great, astonishing and lasting. Thus, this sign will be eternal and shall not fail.… Let us therefore offer ourselves [to others] as a sign worthy of our God and Savior, not only in adhering to the holy precepts but also in embracing the mode of life corresponding thereto, to the end that seeing our "good works" people may "glorify your Father in heaven." To him are due all glory, honor and magnificence, together with his only-begotten Son and the All-Holy Spirit, now and forever and to ages of ages. Amen. — COMMENTARY ON Isaiah 17:55.13