Hi! I'm reading a book called 'Steve Jobs' by Walter Isaacson. There's one passage dedicated to Jobs's return to Apple after his second medical leave. In the beginning of his keynote address he said: I'm vertical, I'm back at Apple, and I'm loving every day of it. What does 'vertical' mean here? It seems to be a metaphor alluding to a person standing straight (vertical) and steady as the symbol of their regained power. Is my understanding correct? Thanks in advance!