"What immortal hand or eye...thy fearful symmetry?-Explain

In these lines from Blake's The Tiger, the poet, being much imprinted by the staggering creation of the tiger. The poet surprises to think who planned the frightful yet well-proportioned shape and body of the tiger.

            The supreme creator has created a terrible beast-the tiger which is full of power, wrath and ferocity. Such a terrible creation requires a Prometheus-like figure full of immense might and daring. It is difficult to settle for the image of the effortless creator of Genesis. Blake wonder at the immense power of the creator and also of the tiger and leaves his identity an open question.