Sentence:  Alternatively, Friedrich Schur (1881, p. 253) used Thomae's (1873, p. 11) definition of projectivity in terms of <WSD>prospectivity</WSD> to prove the fundamental theorem in a manner which is independent of the Archimedean axiom. 
Meaning of the word marked with <WSD> tags:  A projective relationship between a line and itself by projecting onto an intersecting line from a point on another line that intersects at the same point, and then back on to the first line from a different point on the first intersecting line.