中唐時期，韓愈提倡古文，尊孔崇儒，排佛闢老，以明聖人之道為己任。皇甫走出韓愈門下，為文亦屢言聖道。但其關佛不若韓愈積極，在佛教衝擊之下，喜談心性，故雖仍以儒學為依歸，卻亦兼受佛、道影響，而自有新意。他的聖人觀要旨有三 : 其一謂「窮理盡性唯聖人能之」，而以孟、荀為一偏之說。其二謂聖與愚之分在「心」不在「迹」。其三謂士「當以聖人為準的」，取法其「心」而不拘其「迹」。較諸韓愈，更向內傾，更強調「心」的主導力量， 正足以見出儒學由漢至宋、由重外王轉向重內聖之過渡色彩。

In the mid-Tang dynasty, Han Yu promoted guwen (ancient-style prose), elevated Confucius and Confucianism, condemned Buddhism and Daoism, and expounded on the teachings of the great sages of the past. Huangfu was Han's student, and he discoursed on the doctrines of the sages often, too. However, Huangfu argued against Buddhism less ardently than his teacher did. Buddhism was popular then and made an impact on Huangfu; Huangfu also discussed man's Heart and Nature, which were major Buddhist concerns of the time. Although Huangfu remained chiefly Confucian, he accommodated Buddhism and Daoism to a certain extent and contributed to Confucianism with these insights. The essential points of Huangfu's thought on the sage are as follows: 1. The sage is the only one who can fully grasp the Principle of the universe, and live out his Nature accordingly. The theories of Mencius and Xunzi are not complete enough in this regard. 2. The difference between the sage and the foolish is in the "inner heart," not in "outward deeds." 3. Scholars should take the sage as their exemplar, and follow the sage's inner heart, not his outward deeds. In short, compared to Han Yu, Huangfu emphasized the inner more strongly, and the Heart played a more important guiding role in the kind of Confucianism he envisioned. Huangfu reflected the transition and development of Confucianism from the Han dynasty to the Song with shifting priorities from the outer to the inner.