Good scientists study the most important problems they think they can solve. ‘Herbert Spencer and the Law of General Evolution’ was the Spencer Lecture delivered at Oxford in 1963 and printed in Encounter in September 1963. In the seventeenth and eighteenth centuries philosophic writing was marked by its clarity. John Locke is easier to follow than John Donne. The harm Kant unwittingly did to philosophy was to make obscurity seem respectable. ‘Two Conceptions of Science’ was the Henry Tizard Memorial Lecture, delivered at Westminster School in 1965 and reprinted in Encounter in August. The Romantics shunned ‘applied’ poetry – poetry for the occasion, or poetry upon a given theme – because they felt that artistic creation should be a natural and spontaneous upwelling of ideas. ‘Darwin’s Illness’ was published in the New Statesman of 3 April 1964. The greatest liberation of thought achieved by the scientific revolution was to have given human beings sense of a future in this world.