If you are a journalist, following AP or NYT style, you cannot alter the quote at all. You have several choices for dealing with this: You could paraphrase (as suggested), but in that case you do not use quotation marks. You could expand or reduce the quoted text so that it makes grammatical sense in context. Or, if it's imperative that you use the original quote, you can insert bracketed (i.e., "editorial") text within the quotation marks. That is, you might say, "enlarge[s] our thoughts and frees them ...." That last choice is often used in scholarly writing as well.
If you are writing casually, without regard for the finer points of attribution protocol, then I suppose you could reasonably get away with careless quoting. I don't know why you'd want to.