世上本沒有路，走的人多了，便成了路。

Leonardo da Vinci's drawing of a male figure perfectly inscribed in a circle and square, known as the "Vitruvian Man," illustrates what he believed to be a divine connection between the human form and the universe. Beloved for its beauty and symbolic power, it is one of the most famous images in the world. However, new research suggests that the work, which dates to 1490, may be a copy of an earlier drawing by Leonardo's friend.

Facebook forces users to switch to Timeline, making their pasts more visible