Resist coercion; be open to new ideas.

"On résiste à l'invasion des armées; on ne résiste pas à l'invasion des idées."
Victor Hugo
Histoire d'un Crime (History of a Crime) (written 1852, published 1877)

Which I translate:
One resists the invasion of armies; one resists not the invasion of ideas.

Translated by Menkin as
"No army can withstand the strength of an idea whose time has come."

and rephrased as
"There is one thing stronger than all the armies in the world, and that is an idea whose time has come."

Wikipedia suggests "withstand" could be used rather than "resist" and also identifies these alternative interpretations:

• One cannot resist an idea whose time has come.
• No one can resist an idea whose time has come.
• Nothing is stronger than an idea whose time has come.
• Armies cannot stop an idea whose time has come.
• No army can stop an idea whose time has come.
• Nothing is as powerful as an idea whose time has come.
• There is one thing stronger than all the armies in the world, and that is an idea whose time has come.

How about:

Resist coercion; be open to new ideas.

• Transliteration, as I understand it, attempts to be so transparent that the reader of the transliterated version can reconstruct the original.
• Translation would be more free, allowing for example, the substitution of a similar aphorism in the new language for one with similar meaning in the original.
• Interpretation would go beyond translation, to interpret the meaning of the original to the reader of the translated version.

To resist an invading army does not necessarily mean to overcome that army in battle. The French Resistance against the invading Nazis during World War II illustrates a cultural resistance. "One resists an invading army" can be read as an recommendation to do so.

Not resisting the invasion of ideas should not imply that those ideas should be accepted uncritically, but that their import from a foreign culture should not stand in the way of their fair evaluation. Similarly, "one resists not an invading idea" can be read as an injunction against Chauvinism.

So, I will think of Hugo's phrase as meaning, "resist coercion as a matter of principal, but don't be a chauvinistic jerk."