dukkhaṃ kho agāravo viharati appatisso, kaṃ nu khvāhaṃ samaṇaṃ vā brāhmaṇaṃ vā sakkatvā garuṃ katvā upanissāya vihareyyanti?The Buddha then considers whether there is anyone more developed than himself to which he could subordinate himself to. But he sees no-one more accomplished than himself in virtue, meditation, wisdom (i.e. the three-fold path); nor in liberation or the knowledge and vision of liberation. In short he sees no one in any realm to whom he could be a subordinate - not even amongst the gods. Then he decides:
Miserable indeed the disrespectful and rebellious dwell. Which ascetic or priest should I reverence, respect, and dwell in subordination to?
Yaṃnūnāhaṃ yvāyaṃ dhammo mayā abhisambuddho tameva dhammaṃ sakkatvā garuṃ katvā upanissāya vihareyyanti.At this point Brahma-sahampati turns up to praise the Buddha for his decision. He reveals that this is what all the Buddhas of the past have done, and all the Buddhas of the future will do.
I will reverence, pay my respects, and dwell in subordination to that very thing to which I have fully-awakened.
This is a pretty literal account and partial translation of the text. I wanted to convey the raw experience of reading the text in Pāli. But in taking this approach I must then retrace my steps and say more about the context. Indian society, like most societies, was and is hierarchical. We are probably familiar with the ideas of class (varṇa) and caste (jāti). Each person was embedded in a web of social links and obligations. The Chinese called awareness of, and obedience to, this aspect of life: filial piety (孝; xiào). One had obligations to one's parents for instance, to one's spouse and children, and to the king. Another hierarchy existed in religious circles which may have been modelled on social norms. A student lived, as they say, at the feet of their teacher. In taking a teacher one became their disciple, their servant, and one obeyed without question every instruction. Compare this passage from the Visuddhimagga:
Ācariyassa niyyātentenāpi ‘‘imāhaṃ, bhante, attabhāvaṃ tumhākaṃ pariccajāmī’’ti vattabbaṃ.Regarding the word attabhāva PED says it can mean "one's own nature; person, personality, individuality... life, rebirth". So the interpretation could be "I give up my life to you". The point is that without a total commitment from the student, the teacher will not teach them. In the Gārava Sutta three words are used to express this teacher/pupil relationship: gārava, paṭissa, and upanissāya. These more or less correspond to the body, speech and mind aspects of the person.
Dedicating himself to a teacher he should say: "I give up this personality [attabhāva] to you, Sir." (Vism iii.126)
The word gārava (Sanskrit gaurava) is related to 'guru'. The verbal root is not very clear in either Pāli or Sanskrit, but the Indo-European root appears to be *√gu̯er-. The basic meaning is 'heavy', and cognate words in English are: from Latin 'gravis', gravity, grave; from Greek 'barus' baritone, barium. So the 'guru' is someone who is weighty, who has gravitas. The form of Sanskrit gaurava is a taddhita compound which lengthens the root vowel to au, and has the sense of 'related to or connected with what is weighty', which is to say that the student experiences the gravitas of the teacher, how they live their lives, and responds appropriately (gau devolves to gā in Pāli). The attitude of the disciple is 'gārava' respectful. 
The word paṭissa (also patissa) evokes another aspect of India spiritual life. The root here is √śru 'to listen, to hear'. It is one of the oldest spiritual traditions that the way to learn from a teacher is to pay attention to what they say. Older still is the belief that the sages who composed the Vedic hymns first 'heard' them in ecstatic trances brought on by the drug soma.  Truth/reality (both sat) and speech (vac) have always been very closely linked in India, even after the introduction of writing. Unlike contemporary Western society where, except in specialised situations, the word of any person counts for less than a published source, Indian spiritual tradition required personal communication, often under conditions of strict secrecy. The prefix paṭi- (Sk prati-) suggests 'towards'. So paṭissa means 'listening to', 'paying attention'. PED highlights the nature of the guru/disciple relationship when it defines this word as: "deference, obedience."
In the first passage of Pāli I quoted, the Buddha associated the lack of these qualities - appatisso and agārava - with dukkha 'misery, disappointment'. I think he must mean having no one to respect, no one to pay heed to, in other words having no teacher, is a miserable state to be because one cannot make further progress without a guide. So then he ponders under whom he might subordinate himself. Which brings us to the third word: upanissāya. This is a gerund from upanissayati 'to depend or rely on' (from the root śri 'resort'), and means 'in dependence on, protected by; near to'. In the ancient Indian religions, the religious student dwelt with their teacher, in their house, and learned everything at their feet. Of course once teachers started to become itinerant this lifestyle was modified, but the description stuck. It was rather like the old apprentice system in England. One of my Great-great-grandfathers was apprenticed for seven years. For the first 4 years he got no pay, but only board and lodgings (ie. food and a bed). Years 5 and 6 saw him receive a small allowance, and then in his 7th year he started to be paid for his work. He learnt his trade from his master, living and working under his roof and under his authority. In Sanskrit this relationship of subordination to the authority and will of the master is sometimes referred to as upaniṣad 'sitting down near' or 'sitting at the feet of the guru', though the word also came to mean 'a secret or esoteric teaching', or 'the mystery upon which something rests'; and it is the collective title of late Vedic esoteric books 'The Upaniṣads'. The Buddha is clearly concerned to find a teacher. He means to subordinate himself to a teacher, to sit at someone else's feet, as is the custom of his time and place.
So the proper attitude of the disciple, in this traditional view, is total commitment of body, speech and mind; characterised by respect for the teacher's gravitas, paying attention and obedience to the teacher's words, and subordination to the will of the teacher.
The Buddha is portrayed as being quite humble even in the face of his amazing breakthrough. However this humility is replaced by some other emotion (we're not quite sure what) when he realises that he is in no way inferior to any being in the universe (human or divine), and that it would not be right for him to subordinate himself to anyone under those conditions. This speaks to the ancient Indian feeling for order. The universe is an ordered and lawful (dhammatā, niyamatā, or even dhamma-niyamatā) place. The Buddha could not take a teacher of lesser virtue, or lesser wisdom. This would be unnatural. Lacking a being to pay his respects to, he realises that he can direct those emotions towards the dhamma itself. I think dhamma here is slightly ambiguous. I suspect it is deliberately so - the Buddha will respect the thing (dhamma) which he awakened to - whatever that might be! It could mean any or all of: 'thing, teaching, truth, nature, order'. There is an emphasis in the Pāli: tam'eva dhamma 'that very thing' or 'only that thing'. That thing, that very thing, is what we call "The Dhamma", i.e. the Dhamma as a refuge, or as one of the three precious gifts (aka the three jewels) which though singular has many aspects and facets.
- Gārava Sutta. SN 6.2 PTS S i.139. My translations. Also translated in Bodhi The Connected Discourses, p.233-4; online translation by Thanissaro @ Access to Insight.
- Various theories have been put forward regarding the identity of the original soma - since the contemporary soma is not a drug. Since the sages had visions it has often been assumed to be an hallucinogen. However a good case has been made for it be ephedra - If you watch Michael Wood's excellent documentary on Indian history you can see him procuring and taking ephedra in episode one. For more scholarly (less empirical) approaches see The Electronic Journal of Vedic Studies: especially Vol. 9 (2003), Issue 1 (May).
- Those with some Sanskrit may enjoy this little exercise from Deshpande's Saṃkṛtasubohini textbook (chp 14, exercise १.५).
गुरुः कथं गुरुर्भवति? यतो गुरोः ज्ञानं गुरु भवति । ततस्स गुरुर्भवतीति गुरवो वदन्ति । केषाञ्चित् तु लघु भवति । ततस्ते गुरवो एव न वर्तन्त इति सर्वे कुशलाश्सिष्या मन्यन्ते ॥