To understand "The Tiger" fully, you need to know Blake's symbols.
The title seems to be quite simple. It lets us know that the poem is about a tiger. So, we expect it to be just that, about a tiger. However, as we start reading, it becomes clear pretty quickly that this is not just any tiger. It could be a symbol Blake uses to make a far deeper point than something like tigers are scary. It is one of the poem of his collection named: songs of experience. The main theme of the poem is focused on the creator of the tiger and the dwell aspects of the creation. Blake's story of creation differs from the Genesis account. The familiar world was created only after a cosmic catastrophe.
The Tiger is a poem made up of questions. There are no less than thirteen question marks and only one full sentence that ends with a period. It is about having your reason overwhelmed at once by the beauty and the horror of the natural world. The poet repeats the word tiger to emphasize on the meaning and to bring a rythm to the opening of the poem. The repetition of the words also attract the attention of the reader. The poet wonders what created this violent ferocious creature. He referes to the creator as immortal because the tiger is so heartless that it could turn against its creator. That is why the creator has to be immortal to survive an attack from such a fierce creature.
The poet even admires the technique that has been used to create the heart of the tiger with twisted muscels because it has been done so artistically. He also wants to know what chain could keep the brain in its place. The tiger never seems to forgive or forget anything. When the last touch was done the stars threw down their spears. They disaproved the creation because they knew that this creature would bring destruction to the world rather than harmony. The poet questions if the creator was pleased to see the results of his masterpiece.
For Blake, the stars represent