Word choice matters.
The playwright has limited means of conveying an entire world to the audience, and to you, the actor. He has only words. And he has a limited number of them, at that. He cuts out lots of words en route to the final draft of a play, and so every word that he leaves in counts and often has to carry out several assignments at the same time.
Which words he chooses tell you everything you need to know about the play and the characters. The words are your clues to put the puzzle of the play together. Think of the pieces as Easter eggs. In an Easter egg hunt, some of them eggs are so obvious that they dare you to ignore them. Some are tucked behind a vase, their noses sticking out. And some are so hidden that you need to move something in order to find them.
These last clues in a play may not surface enough for you to see them until halfway through rehearsal, but they’re there, hidden in the text. But if you’ve changed the playwright’s words in the course of memorizing your lines, you’ll never find them.
It’s easy to change lines. Sometimes we paraphrase lines to muddle through them because we have a mental block about them, and it gets us to the rest of the scene. Before you know it, we’ve convinced ourselves that that is, in fact, the way the line is written.
Sometimes we change lines because we, personally, would use a slightly different phrase, and so it seems more natural to us to use our own words. We may not even realize we’ve changed them. If someone brings it to our attention, we’ll probably argue with them and stare at the script in disbelief.
Sometimes we change lines because we can’t understand why the playwright wrote it as he did, and rather than figure out the answer to that question (which might have a profound influence on how we play the character), we change the line so that it fits in with our notion of the character. This is akin to taking a jigsaw puzzle piece and forcing it into a place where it doesn’t belong or, even worse, shaving the side of it so it will fit.
And sometimes (horror of horrors), we just think that we, who are so new to the material, know better than the writer who created these characters and slaved over each word in the script for many months.
But word choice reveals character, and so when you change your character’s lines, you change your character. And usually not for the better.
Next time, I’ll give you some specifics about the kind of damage changing the playwright’s words can do. But in the meantime, do your best to memorize his words, and not yours.