A great actor is independent of the poet, because the supreme essence of feeling does not reside in prose or in verse, but in the accent with which it is delivered.
Meaning of the quote
The quote means that a talented actor doesn't need the writer's words to show strong emotions. The most important part is how the actor says the lines, not the words themselves. The actor's voice and performance is what really makes the audience feel the emotion, not just the written text.

About Lee Strasberg
Lee Strasberg was a renowned American theatre director, actor, and acting teacher who co-founded the influential Group Theatre and later directed the prestigious Actors Studio in New York City. He is considered the ‘father of method acting in America’ and trained numerous famous actors and directors over his decades-long career.
More quotes from Lee Strasberg
If we cannot see the possibility of greatness, how can we dream it?
American theatre director, actor and acting teacher (1901-1982)
A great actor is independent of the poet, because the supreme essence of feeling does not reside in prose or in verse, but in the accent with which it is delivered.
American theatre director, actor and acting teacher (1901-1982)
An actors’ tribute to me is in his work.
American theatre director, actor and acting teacher (1901-1982)
The actor creates with his own flesh and blood all those things which all the arts try in some way to describe.
American theatre director, actor and acting teacher (1901-1982)
Art is longer than life.
American theatre director, actor and acting teacher (1901-1982)
Acting is the most personal of our crafts. The make-up of a human being – his physical, mental and emotional habits – influence his acting to a much greater extent than commonly recognized.
American theatre director, actor and acting teacher (1901-1982)