That is why we practice zazen
Shikantaza is to practice or actualize emptiness. Although you can have a tentative understanding of it through your thinking, you should understand emptiness through your experience. You have an idea of emptiness and an idea of being, and you think that being and emptiness are opposites. But in Buddhism both of these are ideas of being. The emptiness we mean is not like the idea you may have. You cannot reach a full understanding of emptiness with your thinking mind or with your feeling. That is why we practice zazen.
– Shunryu Suzuki
from the book “Not Always So: Practicing the True Spirit of Zen”
With thanks to Just Dharma Quotes