New ways/paths are created/opened by walking them.

I'd say

Only by exploring can one discover new routes/ways/paths.

too close to original text.

You are looking for a quotation from Franz Kafka an author from the early 20th Century. I unfortunately cant trace the one you are looking for in English. I however hope that my lead will help others to help you.

@ dannniii Are you sure its Kafka? I always attribute that one to Nietzsche.

Oh, and I thought it was from the Spanish poet Antonio Machado (caminante no hay camino, se hace camino al andar...)

http://www.unmoralische.de/zitate/zitate26.htm
Wege entstehen dadurch, dass man sie geht.
(Franz Kafka, österr. Schriftsteller, 1883-1924)

See also:
http://www.c2-beratung.de/forum/sprueche.html

My leads tell me it was Kafka...it may have been someone else but what is important is that we find the right translation for Jochen.
@Carola and lunanueva: let me look up your leads too....may be they will lead us to the answer...:-)

@ dannniii It was just one of those lines I grew up with and whose attribution to Nietzsche I never doubted. It would seem I was wrong, though there are a few fellow deluded ones out on Google who also give it to Nietzsche.

I should probably add that my translation was mine rather than a widely accepted published one.

@dannniii Thanks for the quotations. Unfortunately my English is not good enough to make a good translation of Kafka's sentence. When I first saw it I could not help thinking of this very popular Spanish poem which deals with this topic.

new paths will emerge, if you will venture out/forth.