Shanti Mantram

शान्ति मन्त्रं
ॐ
स ह नाववातु स ह नौभुनक्तु
सहवीर्यम करवावहै
तेजस्विनावधीतमस्तु
मा विद्विषावहै
ॐ शांतिः शांतिः शांतिः
Swami Dayananda's commentary: http://www.arshavidya.org/literature_sample.html#shanti
May He (the Lord) protect both of us. May He nourish both of us (with knowledge)May both of us make effort for the capacity (for knowledge to take place)May what is studied by us be brilliantly clearLet us not have any misunderstandingPeace! Peace! Peace!
sa ha nAvavatu (saH ha nau avatu)
saH means Ishvara, the meaning of the word tat in the statement: "You are that." tat ivam asi. The meaning of the word tat is the Lord. May that Lord definitely, indeed (ha) protect, bless (avatu) both of us (nau). The word om is also from the same root as for avatu, the root av. ; av is used in the sense of protecting, the one who protects being the source of blessing. Thus, the Lord's name is Om. You can also say he is the one who sustains everything. May that Lord bless both of us, teacher and student.
sa ha nau bhunaktu
May that Lord (saH) definitely, indeed (ha) nourish (bhunaktu) both of us (nau) - that is also in the sense of protection. There is no meaning of eating here; (for in that case, the verb would have to have different endings - Atmane-pada). The sense here is only of nourishing. May he nourish both of us with knowledge. May the Lord indeed, or may the Lord certainly, condoning all my omissions and commissions, being blind to them, bless us and nourish us both. Both student and teacher seek bhagavAn's blessing:
saha vIryam karavAvahai
May both of us together exert, make effort (karavAvahai). What kind of effort? With (saha) vIrya; vIryam here is the capacity required to gain knowledge (vidya-sampAdane sAmarthyam). Whatever is required to gain this knowledge, may we make an effort for that. In gaining this knowledge a certain capacity, certain conditions are required. May we both cultivate those conditions, abilities. There are two types of conditions that have to be fulfilled here. As the teaching takes place, the student is supposed to see the meaning (grahaNa-sAmarthyam). That is a capacity, and it consists of lot of things. In giving the knowledge also, the teacher needs a certain capacity (sAmarthya). Your (teacher’s) memory should help you and you should also be able to see the condition of the listener, and decide what exactly will drive home the idea. There are a lot of things in the shAstra. If we tell all of them in the beginning it will be confusing. Also, you cannot make a statement which will have to be withdrawn later. You have to say the same thing in a form that is understood by the student at the stage that he is at. At one stage one thing is relevant, at another stage, a little more. It all depends on what you have already taught—and what the student has understood. This giving of knowledge (yidyA-dAnam) is not easy, especially if the vidyA has a certain intrinsic difficulty. You have to use words where words have no access, and cannot have access. But only through words you have to communicate. Therefore, you have to make sure you negate what is to be negated and take the student to a corner from where that student cannot but see. This is what they call the analogy of [seeing] the moon [through] a branch - shAkha-chandra-nyAya. nyaaya is a conclusion, a particular fact revealed through an analogy, like an adage or proverb.
This shAkha-chandra-nyAya is a very interesting nyAya. A person wants to communicate his experience of the crescent: moon, the third day moon, let us say. They say it is auspicious to see the third day moon and this person wants to share his experience of seeing it with his friend who is by his side. He says. "Look at the moon." His friend looks at the sky and is not able to see the moon. Here is a problem of communication. He can tell his friend to look up and scan the sky, but the sky is too vast to scan. So he follows a very simple method. He sees a tree and asks his friend to look at the tree and find the branch that is projecting towards the left side of the trunk. The friend says. "Yes. I see it."