Why is this the answer?

The answer is nothing because this is a very famous and clever riddle that plays a super fun trick with words. It uses the word "nothing" in many different ways to make us think hard and notice how one simple word can solve so many clues at once. It is like a secret key that unlocks every lock in the poem. Let's look at the first two lines like a little puzzle: "What does man love more than life, fear more than death or mortal strife." When we think about what people love most of all, it is usually their own life! So, if you love life the most, you love *nothing* more than life. It is the very top of your list. And if you are most scared of anything, it is dying, or "death and mortal strife." This means you fear *nothing* more than death. This is how the word "nothing" is the perfect answer when you are talking about the most important thing. Next, the riddle says, "What the poor have, the rich require, and what contented men desire." Think about someone who is very poor. What do they truly possess? They have *nothing*. Now, think about someone who is very rich and already has all the toys and things they could ever want. What do they still need or "require?" They require *nothing* else! The same is true for someone who is completely happy and peaceful, or "contented." They desire *nothing* more to make their life perfect. The last part of the riddle is also very smart. It asks about a "miser" and a "spendthrift." A miser is someone who is afraid to use money, so he spends *nothing* extra. A spendthrift loves to buy things, so he saves *nothing* at all. And finally, when people pass away, what do they take with them? The riddle says, "all men carry to their graves." The wise answer is that we all carry *nothing* from this world with us to our graves. That is why this simple word is the amazing answer to the whole puzzle.