These wasan primarily clarify the difficulty of receiving shinjin due to it being entirely the working of Amida rather than the development of a practise or attitude based on our deluded, discriminating minds.

44

Through the words of the witness and protection
Of the countless Buddhas throughout the ten quarters,
We should realize that the mind of self-power aspiring for supreme enlightenment
Is incapable of reaching fulfillment.

The first two lines refer to the 17th Vow, which refers to the universal preaching of the nembutsu teaching, or the universality of Amida, who is the Name. Shinran clearly thought that his interpretation of the teachings flowed naturally from the preachings of the Buddhas themselves, as he relied primarily on witness passages for his major doctrinal work "The True Teaching, Practice, and Realization of the Pure Land Way". Though we know that in reality he had non-literal readings of many passages, which can be justified by saying his readings are an expression of having received shinjin, i.e. Amida's mind.

Regarding the latter two lines, Shan-tao famously said that deep mind has a dual aspect: both seeing one's incapability of reaching enlightenment through self-power, and entrusting in the efficacy of salvation through Amida's vow. It is also said that hearing the Name is itself shinjin. Therefore, recognising one's incapability of reaching enlightenment is fundamentally linked to hearing the words expounded in the first two lines.

45

Realization of true and real shinjin
Is rare in the defiled world of the last dharma-age;
The witness of Buddhas countless as the sands of the Ganges
Reveals how difficult it is to attain.

True and real shinjin is rare to realise because we are so attached to the notion of self-power. However, shinjin is still entirely arising from the directing of virtues from Amida to us, so while it is rare it is also not within our sense of control, specifically because our idea controlling it is antithetical to it. In this sense, the question "How do I realise shinjin?" is ill-formed. The fact that so many Buddhas have to preach it shows that it is difficult.

46

If we had not encountered
Amida’s directing of virtue for going forth and returning,
Our transmigration in birth-and-death would have no end;
What could we do then, sinking in this sea of pain?

l.2: the two aspects of Amida’s directing virtue.

If Amida had not made and fulfilled the vow that universalises himself, and we had not encountered preaching of that form that the formless wisdom takes on, then we would have no chance at realisation. All bodhisattvas rely on tariki, and there is nothing that can be done without it, except to remain in a faulty state of delusion.

47

When we entrust ourselves to the inconceivable Buddha-wisdom,
We dwell in the stage of the truly settled.
Those who are born transformed [in the Pure Land] are of superior wisdom,
And they realize the supreme enlightenment.

When we receive the entrusting mind from Amida, we are completely guaranteed to attain enlightenment, and there is nothing at all we can do to separate it. The Pure Land is more like a doorway that we pass through, immediately returning. Therefore going forth and returning are separated by an immediate moment, and in that moment we realise the same enlightenment as Amida.

48

Entrusting ourselves to the inconceivable Buddha-wisdom
Is taught to be the cause of birth in the fulfilled land.
Realization of shinjin, which is the true cause,
Is among all difficulties even more difficult.

Again, realising shinjin is actually "impossible" because it is not us who does the realising, it is gifted to us.

49

Casting off the pain of birth-and-death since the beginningless past,
We are certain of attaining supreme nirvana.
This is through Amida’s directing of virtue for going forth and returning;
Our gratitude for the Buddha’s benevolence is truly hard to fulfill.

Our guarantee of attaining nirvana is entirely through Amida's directing of his virtue to us, rather than by actions we take ourselves in our own life. Everything after that is just gratitude, but we can't really fulfil gratitude of such a vast compassionate act and therefore we "practise" gratitude forever afterwards. This is why people of shinjin forever rejoice.