We might think that the four vows are distinct.
The second vow is often rendered as:
‘Delusions are inexhaustible, I vow to end them’.
On hearing this, we might imagine our goal is to stop all this inconvenient feeling and thinking, and to live in a kind of spacious equanimity for ever.
This is completely mistaken. Our vow is to let everything flooding through and around this person from moment to moment fully live.
We do that by not appropriating this flood of experience to the self. We see this with the third vow, Dharma Gates are endless, I vow to enter them. In other words, Non duality.
The last vow is ‘The Buddha Way unattainable, I vow to attain it’.
The first three vows are an expression of the Buddha Way. The Buddha Way expressed from moment to moment. Listen
Pay careful attention to the words. The Buddha way unattainable, I vow to attain it. But this way of non duality is ungraspable by the I, the source of duality.
The Buddha way is not a something in the distant future. It is Now. Now.