The Lord said
ऊर्ध्वमूलमधःशाखमश्वत्थं प्राहुरव्ययम् ।
छन्दांसि यस्य पर्णानि यस्तं वेद स वेदवित् ॥1॥
The Lord said: They speak of an unfading ashvattha tree with its roots above and its branches below, whose leaves are the sacred metres. One who knows it knows the Veda.