“…As Nauenberg noted further, in Newton's correspondence from 1686 with Halley, he rejected allegations that he learned about the inverse square dependence from Hooke, noting that "Mr. Hook without knowing what I have found since his letters to me, can know no more than the proportion was duplicate quam proxime [approximately] at great distances from the center, 8 only guessed it to be so accurately, & guess amiss in extending that proportion down to the very center.." (Newton 1960) Newton used the word "guess" to indicate that Hooke did not provide any mathematical evidence for his assumption that "attraction always is in a duplicate proportion to the distance from the center reciprocally," as Hooke had written. (Nauenberg 2005) In a letter to Halley, Newton stressed that in this sense "Theory I am plainly before Mr Hook. For he, about a year after [1673], in his Attempt to prove the Motion of the Earth, declared expressely that the degrees by which gravity decreased he had not then experimentally verified, that is he knew not how to gather it from phenomena, 8c therefore he there recomends it to the prosecution of others."…”