In describing the master economist, John Maynard Keynes wrote:

“[He] must possess a rare combination of gifts. He must reach a high standard in several different directions, and must combine talents not often found together. He must be [a] mathematician, historian, statesman, philosopher-in some degree. He must understand symbols and speak in words. He must contemplate the particular in terms of the general, and touch abstract and concrete in the same flight of thought. He must study the present in light of the past for the purposes of the future. No part of man’s nature or his institutions must lie entirely outside his regard. He must be purposeful and disinterested in a simultaneous mood; as aloof and incorruptible as an artist, yet sometimes as near to earth as a politician.”

Memorials of Alfred Marshall, ed. by A.C. Pigou, 1966
p.12, Paragraph 3