The wind is the root of the various functions of all living creatures, and because living creatures are enabled to live by it, therefore is the wind called Prana (or life).
प्राणिनां सर्वतो वायुश्चेष्टां वर्तयते पृथक्। प्राणनाच्चैव भूतानां प्राण इत्यभिधीयते॥