誠齋詩云:「子雲到老不曉事,不信人間有許由」,對許由其人其事,歷來學者或信或疑:信者,如黃元吉《許真君傳記》以許遜為由之後人;疑者,如司馬遷、揚雄、張萱等人;至於堯、許優劣的評斷,學者所見亦異。郭象「堯優而許劣」思維,後世多有附論者,不過,筆者回歸《莊子》文本,認為莊子原意應是「優許而劣堯」。這個差異處實反映出一種「儒、道會通」思維,且具有三種哲學上的意義:一是對堯、許優劣的新詮,雖異於莊子,卻開出「堯優而許劣」與「堯、許一也」兩條思想脈絡。二是會通儒、道兩家思維,將儒家聖人與道家式的「無為」綰合於「堯」。三是將莊子哲學落實於外王事功,看似對立的儒學與莊子,乃得到會通的可能性。
About the stories of Xu You, not all philosophers believed them. Guo Xiang claimed that Yao is superior to Xu You, and many subsequent philosophers accepted his angle. However, I think Zhuang Zi should claime that Xu You is superior to Yao. The opinion of Guo Xiang reflected a thought of ”A Philosophical Synthesis of Confucian and Taoism” and its 3 senses. First of all, Guo Xiang's view is a new interpretation that Yao is superior to Xu You. Besides, it shows a sense of ”A Philosophical Synthesis of Confucian sage and Taoism's Inaction”. The third sense is that it applies Zhuang Zi's philosophy to governance, and it presents a thought of ”A Philosophical Synthesis of Confucian and Zhuang Zi”.