Yengo (1063-1135) gives his evaluation of the mondo, question and answer, which took place between Bodhidharma and the Emperor Wu of the Liang dynasty in the following words:

Bodhidharma came to this country, via the southern route, seeing that there was something in Chinese mentality which responds readily to the teaching of Mahayana Buddhism. He was full of expectations, he wanted to lead our countrymen to the doctrine of Mind-alone which cannot be transmitted by letters or by means of word of mouth. The Mind could only be immediately taken hold of whereby we attain to the perception of the Buddha-nature, that is, to the realization of Buddhahood. When the Nature is attained, we shall be absolutely free from all bondage and will not be led astray because of linguistic complications. For here Reality itself is revealed in its nakedness with no kinds of veil on it. In this frame of mind Bodhidharma approached the Emperor. He also thus instructed his disciples. We see that Bodhidharma's [emptied mind] had no premeditated measures, no calculating plans. He just acted in the freest manner possible, cutting everything asunder that would obstruct his seeing directly into the Nature in its entire nakedness. Here was neither good nor evil, neither right nor wrong, neither gain nor loss...

The Emperor Wu was a good student of Buddhist philosophy and wished to have the first principle elucidated by the great teacher from India. The first principle consists in the identity of being and non-being beyond which the philosophers fail to go. The Emperor wondered if this blockage could somehow be broken down by Bodhidharma. Hence his question. Bodhidharma knew that whatever answers he might give would be frustrating.

What is Reality? What is Godhead?

Vast emptiness and no distinctions whatever [neither Father nor Son nor Holy Ghost].

No philosopher however well trained in his profession could ever be expected to jump out of this trap, except Bodhidharma himself who knew perfectly well how to cut all limitations down by one blow of a sword.

Most people nowadays fail to get into the ultimate signification of Bodhidharma's pronouncement and would simply cry out, Vast emptiness! as if they really experienced it. But all to no purpose! As my old master remarked, When a man truly understands Bodhidharma, he for the first time finds himself at home quietly sitting by the fireside. Unfortunately, the Emperor Wu happened to be one of those who could not rise above the limitations of linguistics. His views failed to penetrate the screen of meum and tuum you and me. Hence his second question: Who are you who face me? Bodhidharma's blunt retort, I do not know, only helped to make the august inquirer blankly stare.