Greta Gerwig didn't want anyone but Saoirse Ronan to play the lead in 'Lady Bird'.
Gerwig (34) is nominated for Best Director at this year's Academy Awards for her directorial debut.
"Saoirse is so transparent emotionally - when you look at her face you can almost tell what she's thinking."
"Not all actors have that. She has this incredible ability to master accents and physicality, and she's spontaneous and alive."
Gerwig said she always knew she wanted to go into directing.
"I spent the last 10 years learning my craft from different angles: from writing, to producing, to acting, to holding up a boom."