An enquiry concerning the principles of natural knowledge

by Alfred North Whitehead

, intersect. In case (i) the three moments are called 'co-level.' In case (ii) there are special relations of parallelism of levels, to be considered later. In case (iii) the locus of abstractive elements and abstractive classes which forms the intersection of

and

will be called a 'rect'; let this rect be named

. Then

is also the complete intersection of