According to this manga on mental health, positive people notice the lady, because they like to have fun! Negative people notice the knife. They are so not fun. Boo.
But what if you're simply not interested in ladies? Not everyone is! Or you are not afraid of knives? Likewise, not everyone is—some have fun...with knives. What if you're interested in ladies, but more interested in knives? Or what if you like both the same? What if you don't like real ladies, but like manga ladies? Or vice-versa? What if you don't like anything? Arrrrrgh.
I actually noticed the page number. 119, huh. So, half-full?