In plain words
For us to recognise such states well, we must practise certain kinds of sādhana. The principle that makes known the principle of all three, this Sāṅkhya, Tāraka and Amanaska, abides in the very seat of our heart. There is ghee in milk, but we do not see the ghee apart from the milk. But when that milk is turned into curd, and the curd is churned into buttermilk, and then it turns into butter, then after the butter is boiled it becomes ghee. When you try to mix ghee into milk, it stays quite apart from the milk; it will not consent to be merged in the milk. Just such is our life. Though the principles called Tāraka, Sāṅkhya and Amanaska are there in life itself, they do not show themselves to us as apart from the body; but once they are recognised through sādhana, it takes a form apart from all of them, the body, the senses, the mind and the intellect, and with no wish at all to merge back into humanity, they set about merging within the very principle of the Ātma. The letter sa stands for the Paramātma; the word aham, the word of Ahaṅkāra, we take to be the jīva; when we utter the form Soham, in which both sa and aham are joined, and hold this very thing in dhyāna, there is the chance for that supreme principle to become clear to us. In our Bhārata it is the custom also to practise sādhanas with this very thing under the name Jīva-brahmaikānanda-sandhāna as well, and also to chant Soham as the Haṃsa Gāyatrī. The word that is without form and name, that is oneness, that is purity itself and that is the witness stands in the supreme principle as the word tat. When man inquires to some extent into this goal called tat, then the word tvam comes forth, which stands as the witness beyond the body. But between these two, the word asi stands ready to join the two. It is the meaning of these three that they give as tat tvam asi, among the supremely sacred Mahāvākyas.