"Hunger is isolating; it may not and cannot be experienced vicariously. He who never felt hunger can never know its real effects, both tangible and intangible. Hunger defies imagination; it even defies memory. Hunger is felt only in the present."

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Why should we try for space travel? It cannot be a substance of any kind that can be expected to pay. It can only be something intangible, not involving haulage, which is at the same time more valuable. There is something like that: Knowledge.

— Willy Ley