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Jerome (aka Eusebius Hieronymus) is best known for his translation of the Bible from Hebrew and Greek to Latin, which eventually became the Vulgate, used by the Catholic Church in the west for centuries following. The all-Latin biblical text is generally considered as important as the Septuagint (the Koine Greek translation of the Old Testament). He also translated a number of apocryphal texts, including Tobit and Judith from Aramaic. Most of this was done of his own accord--he was commissioned by Pope Damascus I to revise the older Latin texts, but eventually took it upon himself to conduct a thorough re-do.
He was born into an affluent family, which was able to provide him with the highest-quality education of the day, and he excelled especially in languages. He learned Hebrew from a converted Jew, and shocked many with his translation of the Old Testament from the Hebrew rather than the Septuagint. In addition to strict translation, he penned prologues to many of the books, and recorded commentaries on books as he completed them.
Jerome traveled widely, and spent time at various monasteries observing ascetic practices. He spent time in the "wilderness," during which, legend says, he removed a thorn from the paw of a lion, which became his pet (this is why, in art, he is often portrayed with a lion). But apparently this legend was actually co-opted from that of a lesser-known saint, Gerasimus.
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I haven't read much regarding Jerome's personal feelings about gender equality, but I do know that he worked closely with a woman named Paula, ministering in Cyprus. Together they founded a monastery, a school, and a hospice.
I don't think I can even make a judgement in this area, because I could find so little (like, nothing) regarding Jerome's stance on the environment. I'll go ahead and make a totally uneducated guess that because of his time in the wilderness, he had some appreciation for God's creation. How's that sound? If you have any input, please let me know.
His translation of the Scriptures was/is the baseline for scriptural orthodoxy, though not everyone in his time agreed (some were weirded out by the Hebrew, and others resented him for "revising" the old Latin). Additionally, his polemic theological writings didn't always win him friends, and his translations of Origen's works (definitely heretical) were suspect.
Dude was smart. Super educated, knew a million languages. I took three semesters of Greek, and I know how intense translating can be. It would take me like five lifetimes to translate the whole Bible. For real. And I would have given him five stars, but that lion story wasn't actually him.
And, finally, a quote:
Be ever engaged, so that whenever the devil calls he may find you occupied."