Wind is essence of the feet. The vital airs are made of wind. Wind is the essence of the sense of touch, and touch is the attribute of wind.
चरणं मारुतोत्मेति प्राणापानौ च तन्मयौ। स्पर्शनं चेन्द्रियं विद्यात् तथा स्पर्श च तन्मयम्॥