Wim Crouwel's 'New Alphabet' from 1967. Timeless and lean in it's form I think because the process was determined by constraint. Namely, at that time, embracing low-resolution-screen-limitation of typography. It was a theoretical exercise, as he says below. We are still talking today, though, about the inclination of type-design towards print rather than screen. His underscored m's and w's and single case character set still feel like a better substitute for the incumbents.
Mr. Crouwel is a young old man. I saw him talk a year or two ago and it was clear that he has always used a total grid in one way or another but in order to free himself compositionally. Something within which to improvise. Never heard anyone before or since make a search for Neutrality sound soulful.