This consists of six main chapters called "adhyaya" and each chapters are divided into sections called "brahmana"
The first section of the first chapter starts with the discription of the horse of sacrifice known as "ashva" for "ashvamedh yajna". The body parts of the horse described here are the parts of the universe we percieve.
In the second section, the origin of this horse (the description of which resembles the universe) is narrated. The ocean is projected the embrio from where this horse emerges. It is also given that the day appeared in front of the horse with special significance and the night appeared behind also to mark the significance. On both the sides was percieved the ocean of origin.(this reminds us the birth of a human being: before birth as foetus form is present in embrionic state in amniotic fluid (ocean of origin here). At the time of birth, surrounded by the amniotic fluid where there was darkness resembling night and now while emerging as child faces the broad day light of the world). As for the birth of the universe,