Grey's Anatomy, Season 4

Meredith:
[voiceover] There's a little animal in all of us, and maybe that's something to celebrate. Our animal instinct is what makes us seek comfort, warmth, a pack to run with. We may feel caged, we may feel trapped, but still as humans we can find ways to feel free. We are each other's keepers, we are the guardians of our own humanity, and even though there's a beast inside all of us, what sets us apart from the animals is that we can think, feel, dream and love. And against all odds, against all instinct, we evolve.