Mundaka-1-1-7-yathorṇanābhiḥ

Sri Shankara’s Commentary (Bhashya) translated by S. Sitarama Sastri

It was said the immortal is the source of all created things. How it is the source is explained by well-known analogies; as is well-known in the world, the spider without requiring any other cause itself creates, i. e., sends out threads not distinct from its own body and again absorbs them itself, i. e., draws them into itself or makes them part of itself; as medicinal plants, i. e., from the corn plant to the immovable, not distinct from the earth, proceed from the earth, and as from the living person the hairs proceed different in nature from him; as in these illustrations, so here, i. e., in the circle of samsara, all the universe of the same and different nature proceeds from the akshara above described, without requiring any other cause; the statement of many analogies is to facilitate easy understanding of the meaning; universe which proceeds from the Brahman proceeds in this order and not all at once, like the throwing of a handful of apples.

Links
Various resources on the Mundakopanishad
Upanishad Series – Mundakopanishad Commentary by Swami Chinmayananda