That a substantial part of Aristotle's works had been lost over time constitutes a great loss to the Western tradition of thought. From the mid-19th Century on, however, through the successive efforts of discovering, compiling and authenticating by generations of outstanding classicists, one long-lost work of Aristotle has been partly restored, approximating its original text bit by bit. This is Aristotle's Protrepticus. Its reconstruction is drawing increasing attention of the Aristotelian scholars worldwide. The philosophical values within Protrepticus are expected to make a real difference to our understanding of Aristotle's ethics, philosophy of nature and metaphysics.