“The hardest thing of all is to find a black cat in a dark room, especially if there is no cat.”

Simplified Meaning:

Searching for something that doesn't exist is extremely difficult, and it can make you feel frustrated or confused. Imagine you're trying to find a black cat in a room with no lights. That task is already tough because it's dark and the cat is black, so it blends in. But it's even worse if there is no cat in the room to begin with. You're investing time and effort for nothing. Let’s say you’re looking for your keys, but you’re not sure if you left them at home or somewhere else. You search everywhere, but you never find them at home because you actually left them at a friend’s house. This can be very discouraging and futile. Applying this to life, think carefully about the things you pursue. Make sure they’re real and worth your effort before spending too much time and energy. It’s important to set realistic goals and know when to let go and move on to something that truly matters.