Surya (the Sun) lightens all beings in the ten different regions with his rays. Surya is the very own identity of Prajapathi, so all beings born in the zones so illumined become the very “self” of Prajapathi. The word “crucial air (prana)” therefore refers to Aditya (the Sun) Itself, for the Sun gives the crucial essence (prana). Since all beings are able to live by utilisation of food, etc., the Sun is also known as the Vaiswanara(Cosmic Universal Personality). The whole universe is of his essence, so he is also known as Cosmic Form (Viswa-rupa).
The year is an pointer of time, according to the location of the sun. Time is but a sequence of days and nights, and these stages are caused by the sun. The spinning of the moon causes stages in fullness. The two forces, the sun and the moon, are outcomes of Prajapathi, so time, which is streaked out by the tropics, seasons, months, etc., is also of the same essence. Prajapathi also has northern and southern patterns.
The observation and worship of Prajapathi in this omnipresent aspect is referred to as “spiritual/inner wisdom (jnana)” itself. Those who are equipped with this inner wisdom and who have mastery over the feelings as well as faith in the Vedas can easily persuade themselves that they are the very Atma(soul). Pursuing the northern path (uttara-marga), they reach the spiritual phase known as the world of the Sun (Surya-loka). That world is the heaven of all living beings. Only those who rightfully involve themselves in their daily duties, without any desire or greed for the fruits thereof, can set foot in the world of the Sun.
The seasons like spring are the feet of the Sun, the sign of time; the twelve months are his distinctive traits; He is the source of the worlds —these truths are conveyed in the fourth and sixth mantras of Prasna Upanishad. The rains are also caused by the Sun, so he is the master of another world too, the third, the heavenly world (dyu-loka).