Tappenden (1995) and Wilson (1992) describe the rich mathematical and historical setting of Frege’s Grundlagen der Arithmetik (1884). They point to the connections between Plücker and Clebsch’s understanding of functions – in the context of the duality principle in projective geometry – and Frege’s functional approach. However, I think more should be said about Frege’s early conception of function, fully developed by Frege in Begriffsschrift (1879). In this talk, I claim that Frege’s early notion of function relies, to a great extent, on Frege’s mathematical work from the late 1870s, and reflects the influence of relevant contributions to projective geometry found in Clebsch and Plücker’s works. In so doing, I provide new textual evidence to Tappenden and Wilson’s account of Frege’s functional approach. I then argue that the concept of function developed in Begriffsschrift is instrumental in Frege’s early mathematical project; shapes the syntax, quantification and calculus of the logical system. The purely syntactical use of the function-argument scheme in the proofs of Frege’s 1879 work shows that the notion of function at play is substantially different to Frege’s mature conception, developed from (1891) on.