They have also suggested that the very concept of abstract numbers - the idea of a oneness,a twoness

题目

They have also suggested that the very concept of abstract numbers - the idea of a oneness,a twoness,a threeness that applies to any class of objects 【and is】 a prerequisite for doing anything more mathematically demanding than setting a table - is itself far from innate.
【】部分让我比较费解,请路过的帮我分析一下吧
原文出处

答案

the idea is