In Laoist writing, the terms used to describe the "B" element at the bottom of the "turning back" diagram are often chosen because they have negative connotations, normally designating something commonly regarded as undesirable and not admirable. "Empty" is one such term - the Chinese words used commonly designate something worthless, or so subtle as to be imperceptible.
Negative terms like "empty" do not express a Laoist judgment that what is referred to is actually worthless.
They refer to how something appears and feels in a social environment governed by competition to achieve social recognition, fame, power, and wealth. In this environment, anything that does not give one recognition and social status will appear and feel "worthless."
But of course it would make no sense to think that everything that appears and feels worthless must be good. This is a "bad interpretation," and we need a better one, as follows: Since competition ("contending") for social status ("yearning for solidity") is one of the main obstacles to achieving internal organic harmony, achieving a high level of internal organic harmony requires giving attention to qualities in oneself that appear and feel worthless because they give one no advantages in this competition. Sayings advocating the cultivation of emptiness are (like many Laoist proverbs) "corrective wisdom," correcting certain common human tendencies by using exaggerated language pulling strongly in the opposite direction. "The greatest solidity will feel Empty." (5[45])
"Empty" in the Tao-te-ching refers to aspects of one’s own being that might appear and feel worthless.
Sunya, in most Mahayana Buddhist texts is not a characteristic of a person’s being at all. The ideal Buddhist is an Enlightened person (not an "empty" person) who perceives all perceptual objects, internal and external, as sunya. Sunya is thus a characteristic of things perceived, not of a perceiving person or a person’s mind.
Sunya does not mean worthless, but refers to the fact that, contrary to what we normal feel, no perceptual object has power-in-itself (sva-bhava) to confirm or disconfirm a person’s sense of self worth. Some perceptual objects seem to have independent power of this kind in themselves, but the truth is that this power is a dependent power, dependent on our own Craving and Clinging (Tanha/Upadana). This means that diminishing Craving and Clinging would also diminish this apparent power of things, until one would come to feel all perceptual objects as "empty" of power to deeply disturb one’s sense of self-confidence (as in "an empty threat"). In earlier Mahayana writings, the idea that the Buddhist goal is to have an "empty mind" is regarded as the Hinayana mistake. That is, if one takes "empty mind" to mean a blank mind, then "blankness of mind" is a perceptual object (it is easy to perceive when one’s mind is blank and when it is full of thoughts), and so is also sunya like all other perceptual objects.
Suzuki’s mention of an "empty mind" in the introduction to his book is somewhat confusing in this respect, because this use of the word "empty" is different from the explanation given above. His meaning in the passage, however, is not so different, because he makes it clear that by "empty mind" he does not mean a blank mind, but a "ready mind," "a mind open to many possibilities."
Although this is a very different use of the word "empty," it is in accord with the meaning of sunya above, as follows: Regarding some things as having power-in-themselves gives a person fixed and inflexible preferences. If my ideas are a source of pride to me, this makes me regard it as crucial that other people recognize these ideas as true, giving such recognition power-in-itself to confirm or disconfirm my self-esteem. This makes me not open to trying to understand other ideas, lacking a "ready mind... open to everything." If I could regard my own ideas, and others’ recognition of these ideas, as sunya, then I would be more open to trying to understand the ideas of others.
An idea similar to Suzuki’s plays a part in Laoism, but it is not connected to any term meaning "empty." It is connected rather to Laoist polemic against "naming." That is, Laoists think that the habit of trying to understand everything in terms of fixed categories ("names") makes us not open to understanding the complex uniqueness of every situation. Releasing the hold that fixed categories have on our minds, making them fixed and rigid, would mean relying on more intuitive and holistic perceptions of the world. This in turn means "turning back" to relying on a mental state that might appear and feel "merged," "muddy," "dull," etc. in a social environment that places a one-sided priority on conceptual clarity. A "Merged" mind is able to understand the unique "hidden essence" of each situation (42[1]). This more flexible mind has some similarity to Suzuki’s "empty mind" as a "ready mind... open to everything."