Described by art historian Robert Rosenblum as having `` almost a generic character , an impersonal textbook idea of a perfect Impressionist painting '' , his work strongly creates atmosphere and his skies are always very impressive . Described by art historian Robert Rosenblum as having `` almost a generic character , an impersonal textbook idea of a perfect Impressionist painting '' , his work strongly invokes atmosphere and his skies are always very impressive .