Understand ‘I am’ – ‘अहम् अस्मि – ‘Aham Asmi’. ‘I’ is the first personal singular nominative pronoun. ‘Am’ is the first personal singular verb and is present indicative of ‘to be’ or ‘to exist’. ‘I’ is ego and ‘am’ is existence. With ‘I’ ‘am’ exists. Without ‘am’ ‘I’ cannot, but with or without ‘I’, ‘am’ exists, and that ‘am’ without ‘I’ becomes ‘is’– the verb expressing existence and being, and is the third personal singular of ‘to be’. ‘I’ the pronoun is the substitute of noun is limited. ‘Am’ the verb that is independent and is limitless. ‘I’ is attributed on ‘am’ and ‘am’ is substratum of attributed ‘I’. ‘I’ is dependent on ‘am’, while ‘am’ is independent from ‘I’. ‘I’ is ephemeral and ‘am’ is eternal.

When you say ‘I am’ you knot ‘I’ the ego ephemeral with ‘am’ the existence eternal, and this knot is worldly I am, a person. You are not ‘I’, you are ‘am’. You are not in ‘I’, you are in ‘am’. Without ego ‘I’ you exist as ‘am’ merely as a pure existence. The mere existence  of ‘am’ without ‘I’ is eternity and is limitlessness. ‘I’ is limiter and bounder of the limitless unbounded ‘am’, and that ‘am’ in its independent and fundamental form is ‘is’, and that ‘is’ is egoless you. That ‘is’ is common on all whatsoever exist, that ‘is’ exists in all at once, and is universal. That ‘is’ is God who is the substratum of all, and that ‘isness’ roots in you as ‘am’ with ‘I’ as ‘I am’. The ‘I’ without ‘am’ is null, and the ‘am’ without ‘I’ is full. Even before you say ‘I am’ you already are as ‘is’. Knowing this ‘is’ is the realization and being in it is the highest liberation.
~Sw. Chidananda Tirtha