"Each has his own tree of ancestors, but at the top of all sits Probably Arboreal"

This quote by Robert Louis Stevenson is a metaphor for the interconnectedness of all life. He is suggesting that although everyone has their own distinct family tree, at the root of all of them is a typical ancestor. This ancestor is described as "Probably Arboreal", which is a referral to the evolutionary theory of the "Tree of Life". This theory suggests that all living things are come down from a single typical ancestor, and that all life is adjoined. By referring to this ancestor as "Probably Arboreal", Stevenson is highlighting the idea that all life is linked which we all share a typical origin. He is also suggesting that although we might have various backgrounds and experiences, we are all part of the exact same household. This quote is a tip that we are all connected which we need to make every effort to acknowledge and value our shared humankind.