In December 1953, Jackson suffered a heart attack, as a result of which directing animator Eric Larson of Disney's Nine Old Men took over as director. By April 1954, "Sleeping Beauty" was scheduled for a February 1957 release. With Larson as the director, Disney instructed Larson, whose unit would animate the forest sequence, that the picture was to be a "moving illustration, the ultimate in animation" and added that he did not care how long it would take. Because of the delays, the release date was again pushed back from Christmas 1957 to Christmas 1958. Fellow Nine Old Men Milt Kahl would blame Walt for the numerous release delays because "he wouldn't have story meetings. He wouldn't get the damn thing moving."