Some music can have multiple ways to be interpreted. In extreme cases (actually in many cases), it can be interpreted as happy, casual, or sad, depending on how you play it. Good lyrics can be interpreted in many ways too, without being known what is the real meaning behind it. In music, ignorance is a good thing, in a sense, because it leaves you opportunity and imagination to interpret in your own way, and assign new meanings to it.
I don't know the name of the song I post here, which is played by Jesse Cook right attached to his version of Sting's "Fragile". Fragile is a sad song. It always reminds me the sheer and mere fact that life on Earth are wrapped in this delicate bubble in the dark immense universe. I give a name "Beyond Fragile" to this song, because it is vibrant and energetic, in contrast to our fragility.
For those who wants to revisit "Fragile", here is Jesse Cook's version.