Raphael Levi learned from Leibniz at a late stage in Leibniz's career. This might be a definite advantage for understanding Leibniz. Leibniz did not elaborate some of the philosophical principles behind the calculus until quite late in his career. If he conveyed them to Levi the latter might have included some interesting explanations in this text. Some examples:
Does Levi comment on the nature of infinitesimals: fictions? ideal entities?
Does Levi mention the idea that equality is a generalized relation of equality "up to", in line with the Leibnizian "transcendental law of homogeneity" which he did not elaborate explicitly until 1710?
Does Levi say anything about the law of continuity along the lines of Leibniz's fairly late text "Cum prodiisset" (1701)?
Two books on Leibnizian calculus were published by his secretary Rafael Levi, see http://opac.tib.uni-hannover.de/DB=1/LNG=EN/CHARSET=iso-8859-1/CMD?ACT=SRCHA&IKT=1016&SRT=YOP&TRM=Raphael+Levi&Submit=go Does anyone know anything about those books? What's in them?
The main title of the two books seems to be:
Calculus differentialis oder Rechnung des Unendlichen des Herrn von Leibnitz
The books date from 1747 and 1776. Thus they appear to be different from the ones mentioned in Beenakker's answer in the name of Schwarzschild. I haven't been able to get a pdf to see what the introduction says. If anyone has the pdf I would appreciate it.
The 1776 entry: http://opac.tib.uni-hannover.de/DB=1/XMLPRS=N/PPN?PPN=031333311 is in manuscript. Whoever has access please let me know.