He confessed it because he not only hoped to have it an arbor but finally failed by having only wild grass, but also realized that it was his sin after a long-time meditation of his failure.

• “过去的生命”之必须忏悔，不仅因它是期以“乔木”而终得“野草”的“失败”，而且因为作者通过对失败的长期反思，悟出那其实是一种“罪过”。