Rabbi Levi ben Gershom, known as Ralbag, was born around 1288 in Provence, in southern France. Throughout his life, Ralbag lived a several Provencal cities including Perpignan and Avignon. Sefer Yechusin reports that his father, Gershom, was a wise and scholarly man. This is also indicated by Sha’arei Tzion’s description of Ralbag (see quote below). According to many scholars, Gershom was none other than Rabbi Gershom ben Shlomo, author of an important philosophical work titled Sha’ar ha-Shamayim. In his commentary to Shemos (34:9) Ralbag cites his grandfather as “my master, my grandfather, Rabbi Levi ha-Kohen. This was likely Rabbi Levi ben Chayim, a prominent rabbinic scholar and philosopher who authored many works including a sefer titled Levayas Chen.
The Chida (in Shem ha-Gedolim) records that Ramban was Ralbag’s maternal grandfather. Although not mentioned explicitly, the Chida seems to be citing Sefer Yechusin. However, a close look at the wording of Sefer Yechusin yields a great deal of ambiguity about this matter. In addition, Ralbag never quotes or even mentions Ramban throughout his writings, a startling fact if Ralbag was indeed Ramban’s grandson. For these reasons, among others, some scholars question whether Ralbag was in fact Ramban’s grandson.
Milchamos Hashem
Ralbag is known as one of the greatest Jewish philosophers of the Medieval period; his philosophical work - Milchamos Hashem was published before he turned thirty. In this lengthy sefer, Ralbag explores the views of earlier philosophers and then states what he believes to be the truth regarding these matters. Some of the philosophical views contained within Milchamos Hashem were subject to the critique of later Rishonim, however, Ralbag’s descendant, Rashbatz (Rabbi Shimon ben Tzemach Duran) composed Levayas Chen, to defend Ralbag’s controversial philosophical views.
Commentary on Tanach
Ralbag is well-known for his acclaimed commentary on Tanach. One unique feature of this commentary are the תועליות or ethical and spiritual lessons learned which he wrote as a summary at the conclusion of a topic or story.
Other Works
In addition to Milchamos Hashem, Ralbag authored:
A commentary of the writings of Aristotle
ha-Hekeish ha-Yashar on logic
books on health and medicine
books on mathematics including trigonometry
a book on astronomy
Yesod Mishnah, an introduction to the Mishnah
Mechokek Tzafon, on Aggadic passages in Bava Basra
Commentaries on the Talmud
The Provencal rabbi and scholar Rabbi Yitzchak de Lattes describes Ralbag in his Sha’arei Tzion:
והרב הגדול הנשיא על כל מעלה, הרב רבינו לוי בן הרב הגדול רב גרשום המוכנה ״מאש ליאן דיבאנויילש, חבר חבורים רבים ונכבדים ופירש כל התורה שבכתב ושבעל פה וביאר ביאורים נוראים בכל חכמה ובפרט בחכמת ההגיון ובחכמת הטבע, ובאלהיות ובלמודיות וברפואות אין כמוהו בכל הארץ, וביאר התורה שבכתב באור נכבד מאוד לא נודעה מעלתו כי אם ליחידים
Fun fact: there is a crater on the moon named after Ralbag.
https://en.wikipedia.org/wiki/Rabbi_Levi_(crater)