The Tree of Life was a painting which was inside the Galerie d'Art de Parisiennes during its grand reopening in the spring of 1909. It was kept in the same room as Bridge over a Pond of Water Lilies, The Kiss, and Scotland Forever!.
After the Twelfth Doctor was pulled into Bridge over a Pond of Water Lilies by an alien, he followed Isabelle's life readings outside of the painting's frame and into The Tree of Life. He then went from The Tree of Life into a painting of horses. (COMIC: Gallery)