An elephant is surrounded by a group of curious blind people. Each person is touching a single body part — trunk, tail, ears, and so on.
The group gets together thereafter, compares notes, and are shocked by what they find. Everyone has a different impression of the elephant. The descriptions offered by each participant is completely different. As a group they’re incapable of describing the elephant because no one is able to see every part.
A great article exploring how important it is to focus on the big picture, even of you’re only working on a small piece of a product.
Source: Seeing the elephant