Badarayana is a very wise man who lived a long, long time ago in a place called India. He wrote a really special book called the Brahma Sutras. This book is all about finding the truth behind everything in the world.
Now, the Brahma Sutras can be a little hard to understand. It's like trying to read a really big and tough puzzle when you're still learning to put together simple puzzles. But, if you try really hard and ask lots of questions, you'll start to understand Badarayana's ideas.
Basically, what Badarayana wanted to do was help people think deeply about the world and understand it in a special way. He thought that if people understood the big ideas of the world, they would be happier and more peaceful in their lives.
So, even though Badarayana is not here today, we still use his big ideas and think deeply about the world he helped us understand.