Conception is the birth process of an artistic idea, from the initial creative impulse through aesthetic refinement, problem-solving, and visualization/realization. Execution is the second half of the creative process: the actual carrying out of the idea, in terms of method and materials, which often involves compromises and alterations of the initial conception. Artists often see the initial conception as the guiding force for their aesthetic decisions, in terms of formal elements of design, and in terms of the expressive content desired. Contemporary conceptual artists place more emphasis on the first part of the creative process; traditional artists are somewhat more concerned with the techniques and methods involved in producing the artwork. The painter Henri Matisse advised, in his essay On Painting, that artists should keep their initial impulse in the front of their minds when working on a painting, to make the best expressive and formal decisions.