The known is limited and will always remain limited no matter the progress we make in science.
The unknown is very interesting and can be alluded as a force that propels all things forward. The unknown is infinite and will remain so, no matter how much of it is revealed.
We are limited when we operate within the boundaries of the known. The unknown is there to be explored and we should do so if we are not bound by the fear of uncertainty and desire an expanded experience.