This is a very short poem, but one in which Walter de la Mare tries to evoke the way in which nocturnal animals such as the owl and the mole, when taken out of their element, are "all but blind" and incapable of functioning in certain surroundings. This is perhaps most clearly expressed by the image of the barn owl that we are given in the second stanza, when we imagine her "blundering on her way" as she crashes into trees and tries to move around. Note the alliteration of the "b" sound in this stanza and how it reinforces this impression.
The final stanza then shifts the focus of the poem away from nocturnal animals and then places it very firmly on us as humans:
And blind as are
These three to me,
So blind to someone
I must be.
The issue of this poem has to do with perspective. To us as humans, a mole and a barn owl are "blind" creatures when taken out of their element. We can look at them and judge them as being blind. However, blindness is a condition that is universal, the speaker says, as it becomes a kind of motif that can provide an apt description for humans and the way that we think we know what we are doing and where we are going but so often travel like the barn owl crashing and blundering around. However, crucially, we do not have the self-awareness to recognise that we are often metaphorically "blind" in our dealings.
I would say that the author in nature is mysterious. He is somewhat a dreamer. What i think about the poem especially the last stanza, he compared himself to those nocturnal animals which are blind in the day but can see or perhaps feel things at night, maybe the author had had an instance in his life that made him realize his blindness towards someone important to him.
The poem is All But Blind by Walter De La Mare