SB 2.10.23

vastuno mṛdu-kāṭhinya-
 laghu-gurv-oṣṇa-śītatām
jighṛkṣatas tvaṅ nirbhinnā
 tasyāṁ roma-mahī-ruhāḥ
tatra cāntar bahir vātas
 tvacā labdha-guṇo vṛtaḥ
Synonyms: 
vastunaḥ — of all matter; mṛdu — softness; kāṭhinya — hardness; laghu — lightness; guru — heaviness; oṣṇa — warmness; śītatām — coldness; jighṛkṣataḥ — desiring to perceive; tvak — the touch sensation; nirbhinnā — distributed; tasyām — in the skin; roma — hairs on the body; mahī-ruhāḥ — as well as the trees, the controlling deities; tatra — there; ca — also; antaḥ — within; bahiḥ — outside; vātaḥ tvacā — the sense of touch or the skin; labdha — having been perceived; guṇaḥ — objects of sense perception; vṛtaḥ — generated.
Translation: 
When there was a desire to perceive the physical characteristics of matter, such as softness, hardness, warmth, cold, lightness and heaviness, the background of sensation, the skin, the skin pores, the hairs on the body and their controlling deities (the trees) were generated. Within and outside the skin is a covering of air through which sense perception became prominent.
Purport: 

The physical characteristics of matter, such as softness, are subjects of sense perception, and thus physical knowledge is the subject matter of the touch sensation. One can measure the temperature of matter by touching with the hand, and one can measure the weight of an object by lifting it with the hand and thus estimate its heaviness or lightness. The skin, the skin pores and the hairs on the body are all interdependent with the touch sensation. The air blowing within and outside the skin is also an object of sense perception. This sense perception is also a source of knowledge, and therefore it is suggested here that physical or physiological knowledge is subordinate to the knowledge of the Self, as above mentioned. Knowledge of Self can expand to the knowledge of phenomena, but physical knowledge cannot lead to knowledge of the Self.

There is, however, an intimate relation between the hairs on the body and the vegetation on the body of the earth. The vegetables are nourishment for the skin both as food and medicine, as stated in the Third Canto: tvacam asya vinirbhinnāṁ viviśur dhiṣṇyam oṣadhīḥ.