Words

Lately I've been having trouble thinking of certain words. When I was trying to come up with the word catechism, first I went through cataract, catharsis, concatenation. When I was trying to remember the name of that YA series I've been meaning to read ("Diverged"), I thought, what is that, diligent, leverage, levitation...? On one hand, it's interesting to see how my brain groups words together. On the other... aren't I too young for this? Should I be eating fish oil or something?