"Failure to read what is happening in another's soul is not easily seen as a cause of unhappiness: but those who fail to attend to the motions of their own soul are necessarily unhappy." - Marcus Aurelius
This speaks to what I can control and what I cannot. The motions of my soul, the ups and downs caused by crests of my life's waves. Others have their own oceans, their own waves to contend with and I should not let the movement of foreign waters move me. But also I should attend to my own soul and not be a boat tumbled against the rocks. I should be the rocks themselves, steadfast letting the years wear me away till I am gone but never letting a single wave dislodge me.