Late at C. Lamb's. Found a large party there. Southey had been with Blake, and admired both his designs and his poetic talents. At the same time he held him to be a decided madman. Blake, he said, spoke of his visions with the diffidence which is usual with such people, and did not seem to expect that he should be believed. He showed Southey a perfectly mad poem, called Jerusalem. Oxford Street is in Jerusalem.