Thankfully, this one contains no operator symbols, and doesn't appear to have been written with a sharpie.
It's a little hard to tell. There's a sort of spirally pattern up at the top. Looks like a shell.
The rest is a quote from Hamlet.
This above all — to thine own self be true;
And it must follow, as the night the day,
Thou canst not then be false to any man.
The image in the bottom right hand corner is a bird of some sort.
Three guesses as to whom the letter is from.