What is the rule about splitting infinitives? How would you rewrite the quote above based on this rule?

read this quote that comes from a popular television and movie franchise:

"To boldly go where no one has gone before."

"to go boldly where no one has gone before."

The rule about splitting infinitives is that it should be avoided. If you can avoid inserting a word between TO and the verb, you should. Split infinitives are grammatically incorrect which is why you shouldn't use them.

So, to correct this quote, you should do the following:

"To go boldly where no one has gone before."