In the Foundations of Arithmetic ¹ — announced in 1879 but first published in 1884 — Frege investigates the concept of number without the help of the tools of the Begriffsschrift, since the philosophical public then as now was not attracted by symbolism. This work was not intended solely for mathematicians. Frege makes explicit in the introduction that the investigation of the concept of number is "common to mathematics and philosophy" and the collaboration of the two sciences was not as close as it should be because the mathematicians rightly reject the "primacy of the psychological point of view in philosophy, even spilling over into logic" (GI., v).