In the first part of his autobiography, Shlomo Ben-Yehoshua narrates his life as a Talmudic scholar in Lithuania. He closes this part with the words 'I took a seat on the Frankfurt post [coach], and set out for Berlin'. The change of place marks the end of one life and, after a 'spiritual rebirth', the beginning of a new life as a German philosopher who later renamed himself 'Maimon'. In this paper I argue that notwithstanding this radical change from traditional Jewish lore to modern European philosophy, Maimon carried over some essential philosophical themes. Specifically I argue that Maimon's major contribution to Kantian philosophy, his critique of Kant's solution of the quid juris problem and his own alternative to it, is based on his assimilation of the Kantian problem to the Aristotelian (Maimonidean) and Neo-Piatonic or Kabbalistic conceptual systems, which he brought with him to Berlin, and on the assimilation of the Maimonidean theory of the intellect to a Leibnizian framework. After an investigation of Maimon's death, burial, and the fate and content of his literary estate (part 1), I turn (in part 2) to Maimon's unpublished manuscript Hesheq Shelomo (...). The Kabbalistic work Livnat Hasapir (...) which forms part of it begins with a discussion of the question whether a similarity obtains between 'separate forms' (...) and 'matters' (...), between the ' spiritual' (intellectual) and the corporeal (...), such that separate forms inform their proper corporeal counterparts and not some haphazardly encountered other parts. Maimon there equates this problem with two others: the relation between an immaterial God and the material world and between the immaterial soul and the material body. I show that the problems discussed in this original context reappear later in a Kantian context, although they are entirely alien to it. Maimon identifies the quid juris problem, the justification for applying categories of the understanding to sensible intuitions, with the problem of the creation of the material world by an immaterial intelligence and with the mind-body problem. Maimon knew that this connection must seem strange to the 'philosophers of the school', i.e. Kantians. Nevertheless he insisted that all these problems are instances of the general question concerning the relation of the (Aristotelian and Neo-Piatonic) 'form ' to 'matter'. However, in his Kabbalistic phase Maimon glossed over the problem that a non-sensible, separate 'form ' cannot be similar to a sensible object with the words 'it will nevertheless have some similarity'. In his later philosophical phase, Maimon rigorously criticized Kant's comparable claim that a concept and an intuition have something in common ('schematism') and thus undermined the core of Kant's theoretical philosophy: the existence of synthetic judgments a priori. Maimon's own solution of the problem is also indebted to his Aristotelian formation. Unlike Kant, Maimon does not conceive intuition as a faculty distinct from thought, but (following Leibniz and Wolff) as unclear thought. Grafting this view onto Maimonides' notion of the intellect and on the doctrine of the unity of knowledge, the knower and the known, the duality of intuition and thought disappears and is shown to be a mixture of unclear and clear concepts which are entities of the same kind. The quid juris problem is thus dissolved: concepts of the intellect are clear; intuitions are unclear, confused concepts. in Numbers 32:33. R. Judah's naïve and matter-of-fact attribution of passages in the Torah to late interpolators stands somewhat in contrast to the harbingers of Higher Criticism found elsewhere in medieval writings. The application of concepts to intuition is possible because concepts are applied to (unclear) concepts, not to alien entities. Moreover, the difference between concept and body also disappears: 'body' is an intuition, a confused concept, an apprehension that is not (yet) clear. I therefore suggest that in addition to conceiving Maimon's turn from Jewish lore to modern philosophy as a 'rebirth', we should also understand it, on the philosophical level, as an assimilation of new insights to an already existing conceptual system which is thereby transformed. The process can thus be understood as 'development'. Maimon's originality can be attributed to his intercultural formation. Furthermore, I discuss Maimon's 'relapse' into the Neo-Platonic patterns of thought. Blumenbach's work on epigenetic generation elicited Mairnon's renewed interest in the doctrine of a 'World Soul' (and the Active Intellect). For three years, Maimon worked with this concept which he dubbed 'Spinozism' and, like some of his contemporaries, he identified with Giordano Bruno's philosophy. Later, in a paper that terminates this relapse into Neo-Platonism, Maimon attempted to retrieve a rational kernel from this philosophy and criticized its style (which was his own too!) as 'Schwiirmerei ', as excessive enthusiastic imagination unrestrained by reason. This relapse also shows that Mairnon's development was not linear. Finally, I argue that Maimon's recurrent commentaries and super-commentaries on his earlier work as well as his autobiographical reflections constructed and reflected his personal identity in spite of the radical changes in his life and thought. [ABSTRACT FROM AUTHOR]