There are countless reasons to garden, but one of the most compelling is to leave our mark on the world. Anyone who has ever carved their name into the top of a school desk or wielded a Sharpie against the wall of a bathroom stall knows the thrill of leaving your stamp in reality. There is something deliciously hubristic about it, some fundamental affirmation of the immortality of the soul. It's like spitting in Death's eye - even if you were eventually busted by your teacher because you carved your last name, too.