Acharya Prashant explains that the sounds 'a', 'u', and 'm' pertain to that which is everything. For a common person, everything is the world, which includes themselves. However, those who know a bit understand that the world is indeed one's reflection, one's projection, one's very shadow. The world and the self cannot be decoupled. Therefore, when one talks of 'all this' (the world), one is actually talking of the mind. The existence of any object, like a pillar, is in the domain of the mind. So, Om says that it contains everything, but it need not talk of this and that in order to explain everything. The Upanishad takes a wiser route; it says, 'All this is Om,' which means all this is mind. So, it is better to talk of the mind. 'Om' is about the mind, and its three components—'a', 'u', and 'm'—refer to the three states of the mind or consciousness. The first state is the waking state (Jagriti), which is referred to by 'a'. In this state, you are called 'Vaishvanar,' the one who is conscious of the world (Vishwa). The second is the dream state (Swapna), referred to by 'u'. In this state, you are a totally different person, and your name is 'Taijasa'. The third state is deep, dreamless sleep (Sushupti), referred to by 'm'. In this state, all gross remnants of personality dissolve, and what remains is a stressless, tensionless relaxation, which can be called bliss. The seed of your existence is still there, but in its most rudimentary, primordial form. When you say 'a-u-m', you have described the mind in its totality, as the mind has no state other than these three. The pronunciation of 'Om' itself is a reminder of this journey, as the sound tapers into silence. This tapering is the essence of spirituality. Om is a reminder that firstly, everything is mind, and secondly, there is peace beyond the mind. This is captured in the form of Om. The purpose and climax of Om is silence. It is a tool, a reminder to fade away, to go beyond the cycle of 'a', 'u', 'm'. Om is not a dictionary word with a literal meaning; it is a powerful instrument, provided we know how to use it.