This article distinguishes between Machian empiricism and the logical positivism of the Vienna Circle and associated philosophers. Mach's natural philosophy was a first order attempt to reform and reorganize physics, not a second order reconstruction of the "language" of physics. Mach's elements were not sense data but realistic events in the natural world and in minds, and Mach admitted unobserved elements as part of his world view. Mach's critique of metaphysics was far more subtle and concerned the elimination of sensory (...) visual imagery from natural science, leaving only concrete elements and functions, very much an inspiration to the young Einstein and Heisenberg and a useful engine of theory construction in physics. (shrink)