Sometimes I think we're alone. Sometimes I think we're not. In either case, the thought is staggering.

Sometimes I think we're alone in the universe, and sometimes I think we're not. In either case the idea is quite staggering.

Either war is obsolete, or men are.

If you want to teach people a new way of thinking, don't bother trying to teach them. Instead, give them a tool, the use of which will lead to new ways of thinking.

If you think you can do a thing or that you cannot do a thing, in either case you are right.

If you are the master be sometimes blind, if you are the servant be sometimes deaf.