What is Bao Zhao's poetic achievement?

Bao Zhao inherited and carried forward the traditional spirit of Han Yuefu and became an outstanding poet representing the progressive trend of thought at that time. His works lashed out at the door-gate system, showing patriotic thoughts and wider social content which are rare in the literature of the gentry. His seven-character poem and miscellaneous poem Yuefu perfected the form of seven-character poem, expanded its influence and made important contributions to its development.