My PhD studies have brought me to Zarahtustra and I've read Hollingdale, Lampert and Loeb and T.K. Seung's is a cut above. Concise, lucid and with deep contextual backgrounds it provides an excellent insight into a challenging but incredibly rewarding piece of philosophy. Even if you are not a student, just a casual reader, this book is a must buy.
This is by far the most insightful and detailed interpretation of Nietzsche's 'Zarathustra'. The literary (e.g. Dante, Goethe) and musical (especially Wagner) associations are particularly valuable. Also Seung's references to Spinoza, the self-avowed Nietzsche's precursor, are pertinent. The reading is backed by textual evidence, whilst the interpreter boldly and imaginatively peers into the essence of this notoriously difficult to understand book for 'everyone and no one'. Far superior to Lampert's 'Nietzsche's Teaching', and many others. Simply look no further if you want a truly mature, rich and honest insight into Nietzsche's masterpiece.
Nietzsche himself acknowledged his debt to Spinoza, but many commentators have not paid much attention to this aspect of Nietzsche's thought. Seung accepts Nietzsche's statement that the Eternal Recurrence is the most important theme in "Thus Spoke Zarathustra." The Eternal Recurrence clearly implies determinism, but Seung points out that this does not exclude free will altogether. He makes a distinction between the autonomous will and the heteronomous will. Zarathustra displays the posturing of the autonomous will in Part 1 of Nietzsche's book, appearing to claim that he as an individual could impose his will on the world. The heteronomous will, by contrast, works with Nature rather than against it. Zarathustra refers to the Will of Life, which Seung understands to be synonymous with Nature. He points out that the idea of working with Nature is similar to the Taoist concept of "wu-wei".
Spinoza's view was that, instead of imagining God as a transcendent Being, God is to be regarded as identical to Nature. There is only one substance, which is infinite and eternal, and this substance is God or Nature. All human individuals are connected to the infinite substance in terms of both mind and body. To quote Seung (p.196), "The identity of the soul and body leads to the recognition of the soul as a cosmic entity. Hence Zarathustra talks to his soul as though it it were a pantheistic deity. His soul is his cosmic self."
Seung's book is not all dry-as-dust philosophy. He draws attention to the "Daughters of the Desert" section of Zarathustra (p.302), in which Zarathustra (or is it Nietzsche himself) imagines himself as a "brown, quite sweet, gold-suppurating" date in the mouth of an African damsel!