“Brexit means Brexit and we’re going to make a success of it,” U.K. Prime Minister Theresa May keeps saying.

But what does Brexit mean? And how do you define success?

Brexiters themselves seem split on the question. Some are convinced that the European Union has been holding Britain back from engaging with the rest of the world and that Brexit will allow the U.K. to become an even more engaged global player.

Others clearly voted for Brexit in protest at globalization, believing that quitting the EU will allow the U.K. to “take back control” from unelected and unaccountable foreign bureaucrats, foreign bankers, foreign capital and foreign workers.

On which side of this divide Ms. May falls remains something of a mystery.