what makes something iconic?

i bought a new journal yesterday! my old journal had this iconic hopper painting which i am sure you are all familiar with.

it's not quite finished, but i've never been able to bring myself to write to the very end of a journal. something about it seems so... final?

SO my new journal has a little bit of infamous british propaganda on it (not to mention a motivating mantra). i found this cool photo of the poster in a window!
redbubble.com