In a letter to Archibald MacLeish, Lincoln Kirsten declares:

"... I want to describe to you in a single word the enthusiasm Portinari's paintings inspired me with. I have seen everything he has executed, including his works in Brazil, I can assure you that they are not only the painter's best piece of work, but also the most beautiful done by any artist whether in North or South America. I think he made a wonderful use of the wall, the paintings are both heroic and sincere, and they really decorated the Library ..."