Guru Dattatreya is primarily considered as an incarnation for the enhancement of right knowledge. Shiva Purana glorifies him as a promulgator of right knowledge. Dattatreya is connected with Yoga and he is considered as Yoganatha. His teachings are based mainly on knowledge and Yoga.

The personality of Dattatreya is somewhat unique in the sense that much has gathered round his name. Datta is refered as Indian Trinity from all it's aspects as is seen that the idea of trinity developed fully into the form of Dattatreya. Dattatreya, in the present form is worshipped as an incarnation, of all the three principal gods, viz. Brahma, Vishnu and Rudra. His triple nature is shown either by three heads or six hands. Sahasrarjuna, one of the devotee of Dattatreya was performing Datt!treya-Yaga, a sacrifice attached to his name.

 

The term trinity (from Lat. trinitas) appears to have been first used by Tertullian, while the corresponding Greek term 'Triad' appears to have been first used by Theophilus, the Christian apologist, an older contemporary of Tertullian.

 

Sanatana Dharma denotes the trinitarian group of Brahma, Vishnu and Shiva; and in Egyptian religion a group of Osiris, Isis and Horus. It is said that Brahma is supposed to be analogue of Saturn of the West, Jupiter represents both Vishnu and Shiva.

 

The fondness of Rigvedic words for the triad is expressed in many ways. It is seen in forming various triads of gods, goddesses and even of the world. The gods are divided into three classes of the terrestrial Vasus, the aerial Rudras, and the celestial Adityas. The most significant group is the representative triad of Fire, Wind and Sun.

 

The Rig Veda as well as the Atharva Veda states the gods to be thirty-three in number—this being several times expressed as "thrice eleven", eleven of the gods are addressed as being in heaven, eleven on earth and eleven in waters (air). Sometimes this threefold division is implied when gods are connected with heaven, earth and waters. We often find in the Brahman as the idea that there are in reality only three gods, Agni, Vayu and Surya. And again they are declared to correspond in respect with Sattva, Rajas and Tamas aspects respectively of the Absolute.

The Brahman has two forms; one corporeal (Mruta) and the other incorporeal (Amruta), the former being unreal and the latter only real and that is lustre (Jyoti) or aditya. Aditya is represented by OM, which has manifested itself in three-fold ways. Vedantic trinity, Mother, Father and Teacher as considered in the passage "Matru Devo Bhava, Pitru Devo Bhava, and Acharya Devo Bhava." All these points to the same thing, namely, the conception of the triune combination of three persons, or gods or elements into one god-head is ancient or Creation, Preservation and Destruction are the three fundamental functions of the creative evolution.

Prajapati creates the world in the form of Brahma, sustains it in the form of the great Purusha and annihilates it in the form of Rudra. Anushasana 14 indicates the three different functions assigned to the Sanatana Trinity, Brahma, Vishnu and Mahesha. It states that the Absolute created Brahma from his right side of the body to create creatures, while from his left side Vishnu to protect the people and when the end of Yuga approached he created Rudra.

It is not always the case that Brahma is regarded as creator, Vishnu as preserver and Shiva or MaheShvara as the destroyer. Brahma sometimes appears as preserver or destroyer and Vishnu as creator or destroyer while various passages would regard Shiva as creator. Thus, in the Epics, the three functions are recognised but the particular god is not fixed. Later on in Puranas, the main function of each god is seen fixed, though he is seen doing the other two functions besides his own proving thereby his Almightiness.

 

but we also find that all the three are so helpful to one another that fascinating stories of each having gone to others have been recorded. Thus we see Mahadeva drinking poison when requested by gods headed by Brahma and Vishnu, or Vishnu saving gods from demons grown powerful with boons from Mahadeva, or Brahma advising gods, who go to him first when any calamity occurs. In short they join hands when a common calamity arises either in heaven or on earth forgetting how the calamity arose.

 

Eshwara: Mahadeva is the supreme god
Vishnu: Superior to Mahat, (the principle of intelligence);
Brahma: Filled with Rajas, engages in creation

In another passage, Vishnu tells Brahma: "Shiva inserted the Linga and your seed in me (the yoni) which in course of time developed into the golden egg." In the same way, in a prayer to Shiva the god is also addressed as Vishnu and Brahma after examining the origin of Trimurti both in its theological and philosophical aspects based on Maitr. Upanishad, that since each sect identifie d its own god with the Supreme Brahman, the Trimurti has a distinct form in each.

The Markandeya Purana contains a phrase "Eka Murthis Trayo Dev!>", which also suggests the same thing. In short, it seems that at the time of the Puranas the idea of Trinity was firmly established in the minds of people and the need of the times invented stories, of course, based on traditions, so that each one feels sure about the power of his god. The idea behind it was to express the synthetic mind which developed right from the Rigvedic times. There is a definitive mention of Vishnu's trinity with Var!ha and Nrusimha faces on both sides as Vishwarupa Vishnu with Nrusimha-Varaha heads. Firstly, actual trinity sculptures, i.e. the three principal gods of the Hindu pantheon viz. Brahm!, Vishnu and Shiva  blended into one either separately on different niches or having one nich or the figure having three heads showing the triple 
nature through their characteristic marks. Secondly, we see the actual temples, having three shrines dedicated to the principal gods. Sometimes such shrines become unique pieces of sculpture in architecture. In such cases the temple itself becomes the trinity. 

Thirdly, we come across icons giving prominence to one of the principal deities, e.g. Shiva is given a prominent place in 
many icons from the South. In the same way Vishnu and Brahma are given due honour the devotees of different times according 
to their religious ideas. Many times Brahma is substituted by the Sun-god. Moreover, there are some cases where triple nature 
of the Sun-god has taken shape at the hands of artists, thus proving the sun-worship of the Sauras. Lastly, it is seen in the icons of Dattatreya who is considered an incarnation of the trinity in general and of Vishnu in particular. The last mentioned icons are met with under another name of Hari-Hara-Pitamaha. It is interesting to note here that even the three principal goddesses viz. Parvati, Lakshmi and Sarasvati, the consorts of Shiva, Vishnu and Brahma respectively, are also represented in sculpture in a triple form. In all these ways, in whatever form the triple nature of the divine is formed, one taing is common that it represents the creative, preservative and destructive aspects of the god concerned. In short, it is the triple aspect of the 
Absolute oat is aimed at. The principle behind it seems to be that all the aspects are from one single source and it is the work 
of the Absolute. Men may give that Absolute any name and represent Him in any form.121 In India it is common that a devotee 
regards his god as the highest deity and the same has happened in this case.