Dear friend, all theory is gray

From Faust Part I by Johann Wolfgang Von Goethe. Mephistopheles speaking.

Dear friend, all theory is gray,
And green the golden tree of life.

Grau, theurer Freund, ist alle Theorie,
Und grün des Lebens goldner Baum.

To the extent that we live into the future, we, perforce, live within models, theories, assumptions that allow us to forecast what is likely to happen. All such models are proxies for reality, all are grey compared to the green of the golden tree of life. Committed to the future, it is easy to lose touch with the green of the present.