The sage is not humane.[3]
He regards all people as straw dogs.
The space between Heaven and Earth is like a bellows, isn't it?[4]
While vacuous, it is never exhaustible.
When active, it turns out even more.
(To talk too much will surely lead to a quick demise.[5]
Hence, it is better to keep to tranquility. )[6]

Annotations:
[1] Heaven and earth appear as physical and natural existences. They follow the way of spontaneity inasmuch as they have no preferences for anything in the world. They let all things be what they are or let them go through a natural cycle, for instance, the change and replacement of the four seasons, the life and death of human beings, the appearance and disappearance of plants, the shift of day and night, so on and so forth. By this statement Lao Zi attempts to explain the fact that Heaven and earth have no such feelings, emotions, affections, likes or dislikes as human beings do.
[2] The Chinese term chu you (straw dogs) refers to straw images of dogs used as sacrificial offerings at ceremonies such as those for worshiping Heaven or praying for rain. After the ceremonies they were discarded as worthless. "Straw dogs" serves as a metaphor, suggesting that Heaven and earth show no sympathy for anything or anybody. They themselves stick to the way of nature, and also let all others hold to the way of naturalness so as to preserve their respective selves or egos. This obviously corresponds to Lao Zi's conception that "Man follows the way of earth; earth follows the way of Heaven; Heaven follows the way of the Dan; and the Dao follows the way of spontaneity."
[3] "The sage is not humane." This is equal to saying that the sage, alike Heaven and earth, has no preference for or benevolence toward anything or anybody, but simply follows the way of naturalness without being pretentious or imposing. This type of sage is the Daoist (Taoist) sage, different from the Confucianist sage and pursuing great humanity for all instead of limited humanity for a few. He seems to be equivalent to the "man that follows the way of earth" as recommended by Lao Zi.
[4] Talking about the universe, Lao Zi exhibits his individual insight and striking imagination. As a result, he likens the vast space between Heaven and earth to a bellows, which is characterized with such features as emptiness, productiveness and inexhaustibility. The image itself is fresh, individual and impressive, well exemplifying the style of Lao Zi as a poetic philosopher or philosophical poet.
[5] By "To talk too much" (duo yan) is meant too many political orders, monarchical decrees, secular moral lessons, etc. The Chinese word shu can be understood as su, rendered in English as "soon" or "quickly." The sentence means that if a state coerces its subjects, perhaps by issuing too many orders or instructions, it will surely find itself running counter to its goals and speed up its demise. As a matter of fact, an efficient government does not have to issue a plethora of rules, regulations or laws. It has been proved historically that the more the official orders that emanate from the government, the less effective they are and the swifter the decline of the prestige of the government. Such a situation leads to a government that only has the ability to issue political orders, and lacks the ability to carry them out.
[6] Contained in many editions of the Dao De Jing is the expression bu ru shou zhong, which has been translated into English as "holding on to the mean" by Mr. Robert G. Henricks, or rendered literally as "keep to the center" by Prof. Chan Wing-tsit. These renditions are rather misleading because they tend to make the reader conceive this notion from a Confucianist standpoint. Lao Zi scholars such as Yan Lingfeng and Chen Guying assume that the Chinese word zhong (center or the mean) may be a printing error or misspelling of chong (empty or vacuous). Other scholars tend to agree that the term zhong (center) might stand for the center of a bellows, which is empty or void inside. In addition, scholars like Ma Shulun and Gao Heng proclaim that the last two lines ("To talk too much will surely lead to a quick demise. Hence it is better to keep to tranquility.") do not fit into the context at all. That is why Prof, Gu Ji inserts them in the original Chapter 9 (DDJ). No matter which is the case, we reckon that the concept of zhong is characterized by such features as emptiness and inexhaustibility, having nothing to do with the doctrine of the mean as conceived Confucianist terminology.

Commentary:
In this chapter Lao Zi seems to focus on discussing the inhumanity of Heaven, earth and the sage, and the character of the Dao. Yet, by reading between the lines one can discover that Lao Zi's philosophy

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