Mendelssohn’s Philosophical Writings, published in 1761, bring the metaphysical tradition to bear on the topic of sentiments (defined as knowledge or awareness by way of the senses). They include a nuanced defense of Leibniz’s theodicy and conception of freedom, and examination of the ethics of suicide, an account of the mixed sentiments so central to the tragic genre, an hypothesis about weakness of will, an elaboration of the main principles and types of art, and a brief tract on probability theory, aimed at rebutting Hume’s skepticism.