Sri Aurobindo translates Brihadaranyaka Upanishad, Chapter 1, Section 1, Verse 1: “OM. Dawn is the head of the horse sacrificial. The sun is his eye, his breath is the wind, his wide open mouth is Fire, the master might universal. Time is the self of the horse sacrificial. Heaven is his back and the midworld his belly, earth is his footing, — the regions are his flanks and the lesser regions his ribs, the seasons his members, the months and the half months are their joints, the days and nights are his standing place, the stars his bones and the sky is the flesh of his body. The strands are the food in his belly, the rivers are his veins, his liver and his lungs are the mountains, herbs and plants are his hairs, the rising is his front and the setting his hinder portion, when he stretches himself, then it lightens, when he shakes his frame, then it thunders, when he urines, then it rains. Speech, verily is the sound of him.”
“As above, so below.” We see here a symbolic representation of the material existence of the universe that matches up universal phenomena with the specific characteristics of the horse. The microcosm and the macrocosm are One. The imagery attempts to convey a truth that unites all existence. Our normal view treats each of these as separate and distinct.
In modern Western science, the study of fractals shows that they always repeat the same pattern from the universal to the microscopic scale. The Rishis anticipated this in their description of the sacrificial horse as the form and pattern of the creation.
Sri Aurobindo comments: “Ashwa meant originally ‘being, existence, substance’. From the sense of speed and strength it came to mean ‘horse’. The word is therefore used to indicate material existence and the horse … is taken as the symbol of universal existence in annam. The horse is symbolic and the sacrifice is symbolic. We have in it an image of the Virat Purusha, of Yajniya Purusha, God expressing himself in the material universe.”
Sri M. P. Pandit notes: “The Horse is not a figure of this gross material universe alone. For Time is his body, his substance: the very texture of his being is made of Time which is non-material, though it manifests in physical Space as it does in the other extensions of Space. Earth is his footing. The material extension of Earth is the feet, the foundation created by the Power in manifestation. The Mid-region, antariksa, is his belly wherein all is seized and consumed. Heaven, the freer spaces of ether, the domain of purer Mind, is his back, the part on which this manifest creation rests. … Periods of Time, the Seasons governed by the movements of the sun and stars are his members; months and fortnights set by the moon are that on which he stands. Thus does the manifesting Power cover in its self-extension all the three worlds of our creation in the dimension of Time moving in Space.”