Nathan laughs when his grandfather describes him as a "cool cat." "that's how we used to describe someone who is neat, pleasing, good," his grandfather says. "not anymore," nathan replies. this exchange reminds us that language is

I believe the answer is: Arbitary

Arbitary in this context refers to a fact that a word in a certain language could be perceived differently by one person to another.
Factors that could influence this different perception could include things such as age, culture, experience, etc.

Hamlet's fourth soliloquy is probably his most famous one - "to be or not to be."it is rather different from his previous soliloquies because now he is contemplating something that didn't come up before - suicide. he is thinking whether it is worth it to fight to find his father's murderer when in the end all of them are going to die, so why not die sooner than later. he is contemplating if he should go on fighting or just kill himself and end it all, which is why this soliloquy in particular is rather depressing, hesitant, and gives a deeper insight into hamlet's madness.