Zen's concern with "reality" vs. being in the present

In "Zen Mind" Suzuki says: "The true purpose is to see things as they are, to observe things as they are, and to let everything go as it goes". To see things as they are... doesn't that involve an understanding of past and future? Past and future are part of what it is... no? So my question is... if Zen is so concerned with seeing things as they are, why is it only concerned with the present? Isn't the past and future part of what it is? If your mind is in the moment, doesn't it miss the future and past?