Northward path of the sun. (Glossary for the Vahinis)
Krishna said, ‘the Yogis who practise Nishkama karma pass away in Tejas, during the day, while there is light, in the bright half of the month, and in the six month period of Uttarayana. They have as their first state Agni, or fire. Hence their path is known as Devayana or since Agni is known also as Archi in the Vedas, Archiradimarga. Such Yogis emerge from Prakasha (Effulgence), and travelling through Prakasha, they merge in Prakasha itself. They attain Brahman and are not born again.
The Yogis who practise Sa-Kama-Karma pass away in Dhuma (smoke) at night, during the dark half of the month, during the six-month period of Dakshinayana; they pass along Dhumadimarga and reach Swarga, or Heaven, and there enjoy the pleasures they have yearned for and worked for. When the stock of merit is exhausted, they are born again. (GV, p. 163)
Uttarayana is the period when no dot of cloud or whiff of fog contaminates the vast dome, and the sun shines in all its glory. This is the gross meaning; but there is a subtle one too. The heart is the inner sky. There, the Sun that shines is Buddhi, or intelligence. When the clouds of ignorance, the fog of egoism, and the smoke of attachment hover in that inner sky, the sun of intelligence is hidden and things look murky and are mistaken. Uttarayana of the heart is when the inner sky is clear of all these, and when the sun - the Jnana bhaskara - the Sun of wisdom - shines in full splendour. (GV, p. 164)
From today the sun starts on his northward journey. What does the north signify? It is considered the direction leading to Moksha (Liberation). The sun is said to move towards Himaachala. Himaachala is made up of two words: Hima + Achala. ‘Hima’ means that which is white as snow. ‘Achala’ is that which is firm and unshakable. What is the place to which this description applies? It is the region of the heart. In a heart that is pure and steady, the sun of Buddhi (the intellect) enters. There is no need to undertake a journey in the external world. The Uttarayana (or the Northward Journey) means turning the intellect inward, towards the heart. The bliss that is experienced within alone is true bliss for man. All other external and sensory pleasures are ephemeral. Only the Atmic principle is pure, permanent and infinite. This has been termed the abode of Moksha (Liberation). The journey to Moksha is called the quest for liberation.
Sankramana is the time when the inward journey towards a pure and unsullied heart is made. Just as the sun embarks on his northward journey, Sankranti is the day on which the intellect should be turned towards the Atma for Self-realisation.
The Vedas has declared the Uttarayana as a sacred period. The great warrior Bhishma, lying on a bed of arrows, waited for 56 days for the advent of Uttarayana to end his life. The puranas have stated that whoever passes away in Uttarayana will attain liberation. (SSS Vol.29, pp. 21-22)