Agni

Om Mahajwalyei Vidmahe
Agnidevaya Dhimahi
Tanno Agnih Prachodayat

Agni (Fire) is the deity that represents all the other deities. Agni is said to be the mouth of the gods. Agni is known as the messenger of the gods. Whatever man has to say to the gods, to the higher powers, he conveys it through Agni. The importance of Agni is chronicled quite elaborately in the Vedas, with more than two hundred Sooktas in its praise. It would be no exaggeration to term Fire as among the most important of the Vedic Pantheon of Deities. Two of the four Vedas begin with eulogies to Agni. The very first hymn of the hoary Rig Veda is devoted to this mighty bull among deities - “Agnim eedE PurOhitam Yagyasya dEvam Ritvijam” says the first verse, exhorting us to pay obeisance to Agni as the leader and the deity of all sacrifices. This is no mere flash in the pan, for we find the venerated Sama Veda too devoting its very first verse to this fiery god -“agna AyAhi veetaye, griNAnO havya dAtayE”.
What is the reason for the extremely high pedestal on which the Shruti places the Fire God? Why should this august body of unauthored wisdom devote litany after elaborate litany to this element? Though the other four elements are no less in importance, we find the Vedas almost obsessive in their focus on Fire. The reasons are not far to seek. It is Agni, which makes Sacrifices, the various Yagas and Yagyas, possible. As we know, everything has its roots in Yagyam--all Creation came out of a Yagyam performed at the Cosmic Beginning, as described by the Purusha Suktam.
In the order of Creation, Agni is the third to emerge, the first being Atmosphere, says the Shruti -
“Atmana Akaasa: sambhoota:, Akaasaat Vaayu:, Vaayo: Agni:”.
Only from Fire did the other two elements, Earth and Water, came into being—

“Agne: Aapa:, Adbhya: Prithivi”.
The Purusha Sukta ascribes exalted origins to Agni - right from the Lord’s face (mouth) - 

“Mukhaat Indrascha Agnischa”.
Apart from being one of the five basic elements, Agni is also acclaimed to be the hidden essence of Water -“na apsu mootra pureesham kuryaat--guhyo vaa esha: Agni: iti vadanta”. The very same Shruti tells us that birds do not stay on earth in the night, because it appears to burn in the night. Thus, Agni's influence extends over the other elements too.
Management experts speak of having a “fire in the Belly”, to describe an unquenchable urge for achievement. They would be surprised to know that everyone has fire in their belly-achievers as well as others. Shastras tell us that it is the “Jaataraagni” or the digestive fires located in the intestines, which enable assimilation of food and afford nutrition to the body. The Lord says in the Gita that it is He Himself, who resides in beings as this “Jaataraagni” and enables digestion of all kinds of food—

“aham Vaisvaanaro bhootvaa praaninam deham aasrita:
Praana apaana samaayukta: pachaami annam chatur vidham”.
The Brihadaaranyaka Upanishad too bears out this proposition of the Lord being the Digestive Fire, without whose aid no food could be assimilated - 

“ayam Agni: Vaisvaanaro yo yam anta: purushe yena idam annam pachyate”

Paradoxically, this Holy Fire is more beneficial to us, the closer we get to it, and tends to scorch us only if we stay away due to indolence or ignorance.