Todalatantra 2.1

2.1

śrīśiva uvāca
śṛṇu devi pravakṣyāmi yogasāraṃ samāsataḥ
ūrdhvamūlam adhaḥśākhaṃ vṛkṣākāraṃ kalevaram //

The noble Śiva said:
Listen, O Goddess, I shall proclaim the essence of yoga in brief.
The body is like a tree whose roots are above and whose branches are below.