Notice the use of a word repeated in lines such as these:

(i) On pads of velvet quiet,
In his quiet rage.
(ii) And stares with his brilliant eyes
At the brilliant stars.

What do you think is the effect of this repetition?

The repetition is a literary device that repeats the same words or phrases to emphasize a concept. Here, in the poem the repetition of 'quiet' is used to emphasize the tiger's helpless silence. ‘Velvet quiet’ refers to the quiet velvet pads of the tiger, which cannot run or leap. They can only walk around the limited space in the cage. It also gives prominence to the rage that is building inside the tiger. The tiger wants to wander in the wild but he has to walk with quiet steps in his little cage unwillingly. The poet has repeated 'brilliant' to bring into notice the tiger's aspiration for freedom. As we know, a tiger's eyes are shining and glowing. With those shining eyes, he keeps staring at the shining stars and wishes to free like them. As the stars are inhabiting a place which is their natural home, the tiger also wants to wander around in the forest because that is the place where he belongs to.