Metaphor also denotes rhetorical figures of speech that achieve their effects via association, comparison, or resemblance (e.g., antithesis, hyperbole, metonymy, and simile, which are all types of metaphor)"
-Wikipedia

From the picture above, I can see that people are trying to make things easier by making old inventions then upgrade it into something new. To make these kind of things is not an easy task, we must first broaden our mind and think what people want.