  Ibn Tibbon’s Perush ha-Millot ha-Zarot was the first major philosophical lexicon written in Hebrew. It was written not as a general introduction to philosophy, like the work of his predecessors, but as a glossary to one translated text: Maimonides’ Guide of the Perplexed. In fact, however, it is much more. It includes extended discussions of key terms, and works as both glossary and lexicon, introduction and primer. Many philosophical ideas appear in Hebrew for the first time in the glossary; and there is evidence that the text itself was studied independently, as a general reference work or study aid.