A quotation by Apollonius

The third book [of Conics] contains many remarkable theorems useful for the synthesis of solid loci ... the most and prettiest of these theorems are new, and it was their discovery which made me aware that Euclid did not work out the synthesis of the locus with respect to three and four lines ... for it was not possible for the said synthesis to be completed without the aid of the additional theorems discovered by me.
Preface to Book 1 of Conics