"Pure" must be understood in the sense of transcendent.
But what is a pure man?—The pure men of old acted without calculation, not seeking to secure results. They laid no plans. Therefore, failing, they had no cause for regret; succeeding, no cause for congratulation. And thus they could scale heights without fear; enter water without becoming wet; fire, without feeling hot. So far had their wisdom advanced towards Tao.
"The world-spirit is a good swimmer, and storms and waves cannot drown him."—Emerson.
The pure men of old slept without dreams, and waked without anxiety. They ate without discrimination, breathing deep breaths. For pure men draw breath from their uttermost depths; the vulgar only from their throats.
"Uttermost depths" is literally "heels," but all the best commentators take the sentence to mean that pure men breathe with their whole being, and not as it were superficially, from the throat only.
This passage is probably responsible for the trick of taking deep inhalations of morning air, practised (not without scientific foundation) by the followers of the debased Taoism of modern times. Other tricks for prolonging life, such as swallowing the saliva three times in every two hours, etc., are more open to adverse criticism. See the T'ai-Hsi-Ching.
Out of the crooked, words are retched up like vomit. If men's passions are deep, their divinity is shallow.
The pure men of old did not know what it was to love life or to hate death. They did not rejoice in birth, nor strive to put off dissolution. Quickly come, and quickly go;—no more. They did not forget whence it was they had sprung, neither did they seek to hasten their return thither. Cheerfully they played their allotted parts, waiting patiently for the end. This is what is called not to lead the heart astray from Tao,
By admitting play of passion in the sense condemned in [ch. v]. which would hinder the mind from resting quietly in the knowledge of the known.
nor to let the human seek to supplement the divine.