The old adage that going from zero to one child is harder than going from one to two (did I just blow your mind with all that math) has certainly been true for me.
I think that as a new parent you're bombarded with so much new new new. New situations like dealing with major diaper blowouts. New sleep schedules (or lack thereof). New feelings of inadequacy and what the f&*$ am I doing and why did I think this parenting thing was a good idea.
Not so much with two. I'm a pro at diapering one-handed, at knowing that a baby is generally going to wake up during the night, especially nights when I'm sick or haven't gotten much sleep. Oddly, I'm much more relaxed about getting out of bed to tend to Kid B than I was with Kid A.
the nature of suffering and discovering one's true self.