Ḥasdai Crescas's Light of the Lord is one of the most brilliant works of mediaeval Jewish philosophy – quite possibly the most brilliant. Roslyn Weiss's first complete English translation is one of the finest translations of any mediaeval Jewish philosophy – quite possibly the finest. This book is a philosophical event. It is essential reading for anyone working in mediaeval philosophy, Jewish philosophy, and philosophy of religion. It is fitting that this quite perfect book is so magnificently produced by Oxford University Press.

Crescas (c. 1340–c. 1410) was a rabbi and leader of the decimated Jewish community in Spain. He was a student of Rabbi Nissim ben Reuven Gerondi, a famous talmudist, colleague of Rabbi Isaac ben Sheshet, a famous jurist, and teacher of the philosopher Joseph Albo, whose work has been the subject of an excellent recent study (Joseph Albo on Free Choice, 2017) by Shira Weiss (no relation to the translator). Light of the Lord is Crescas's major work. There have been English translations of some parts, but nothing remotely near the complete translation Weiss has finally provided us.

I'll first say a little about Light of the Lord and then a little about this translation. As for the substance of Light of the Lord, the book covers the full gamut of Jewish philosophy and theology. Crescas treats every issue on every side, for and against, from the perspective of philosophical speculation and from the perspective of religious tradition. Every page is brimming with imaginative ideas, powerful arguments, and devastating objections.

The treatment of philosophical principles is organized by their fundamentality to the rest of the Jewish tradition. The first ‘Book’ is about the existence and nature of God, and includes a deep critique of Aristotelian physics, a critique that might have indirectly influenced Galileo. The second ‘Book’ is about divine knowledge, power, providence, prophecy, free will, and the purpose of creation. The third ‘Book’ is about creation, immortality, resurrection, prayer, and repentance, among other topics. The fourth ‘Book’ is about the multiverse, astrology, amulets, demons, reincarnation, and mysticism, among other topics. The discussion of many of the topics in the third and fourth ‘Books’ is quite short.

Crescas is in conversation with previous Jewish philosophers, especially Maimonides and, to a lesser extent, Gersonides. Like his predecessors he brings together the God of the Patriarchs and the God of the philosophers. But when he takes issue with his philosophical predecessors, Crescas tends to be more representative of popular Jewish belief. As opposed to Maimonides, God turns out to be less abstract and piety less intellectual. Whereas Maimonides argues that God has no positive attributes, Crescas argues that God has positive attributes. Whereas Maimonides grounds our immortality in intellectual attachment to God, Crescas grounds our immortality in our love of God. If there is any unifying theme of the book, it is love. As Weiss puts it on the first page of her introduction:

Crescas's traditionalism does not mean that he always follows the familiar. He is an independent thinker, covering unusual topics and usual topics in unusual ways. For example, a brief chapter defends the conclusion that there are multiple universes. More controversial would be his lengthier discussion of free will. Jewish philosophers tend to take a libertarian view about free will: we have it, and it is not compatible with determinism. Against the trend, Crescas defends compatibilism by distinguishing between actions being necessary ‘in respect of themselves’ vs ‘in respect of their causes’, though he includes a warning:

I can hardly do real justice to the substance of the book in a review. So I turn now to the translation. Some translations of Jewish mediaeval philosophy include many prefaces and introductions. Sometimes they are helpful; sometimes not. They can distract from the work translated, and spread it across multiple volumes: the translation of Maimonides (Shlomo Pines, 1963) runs across two big volumes; the translation of Gersonides (Seymour Feldman, 1984–1999) runs across three big volumes. Roslyn Weiss keeps the spotlight on Crescas, and amazingly keeps the translation to a single volume.

Her introduction is to the point: she covers Crescas's life, the structure and substance of his book, and the nature of the translation – all within fifteen pages. Her footnotes throughout are as succinct as they are helpful. These provide references, alternative readings from the manuscripts, and explanations of tricky arguments. The only criticism I have – my only criticism of the whole effort – is minor: when Maimonides is discussed by Crescas, references to the Guide are often not provided in the footnotes. These would not be hard to provide, and would be at least as useful as other references provided.

I checked the translation against the Hebrew (in Shlomo Fisher, 1990) at some random paragraphs, and found Weiss extremely faithful to the original. Where she departs – for example, in splicing extremely long sentences – her decisions are correct. Where anything is confusing in the translation, it is confusing in the original. Light of the Lord is not an easy book.

Jewish philosophy flourished in the Middle Ages, and suddenly disappeared. Light of the Lord was probably the last great light of Jewish philosophy, though Albo's Ikkarim deserves further study too. A different style of theology and mysticism took its place, and remains in place in the religious Jewish context. Meanwhile, the Jewish academic context would mix careful intellectual history with ropey continental theology – not much concerned with questions about the nature of God, or with the justification of religious principles.

However, a few philosophers are trying to revive Jewish philosophy in the spirit of Maimonides, Crescas, et al. – investigating Jewish principles with the rigour of contemporary analytic philosophy, even while drawing from traditional theology and mysticism. Whether they will succeed against the opposing forces is much in doubt. But this translation will hopefully inspire further serious work in Jewish philosophy, and draw others in the English-speaking world into Jewish philosophy. The translation comes not a moment too soon. That there has not been a complete translation until now is scandalous. The future of Jewish philosophy will be deeply indebted to Roslyn Weiss.