In his foreword to the 1967 edition of the book, C. P. Snow describes the Apology as "a passionate lament for creative powers that used to be and that will never come again".

He began writing on this subject when he was invited to contribute an article to Eureka,[2]: Preface  the journal of The Archimedeans (the Cambridge University student mathematical society).

[2]: Preface Hardy wanted to write a book in which he would explain his mathematical philosophy to the next generation of mathematicians.

One may believe that it is the relative sparseness of number theory in applied mathematics that led Gauss to the above statement; however, Hardy points out that this is certainly not the case.

What Gauss meant, according to Hardy, is that the underlying concepts that constitute number theory are deeper and more elegant compared to those of any other branch of mathematics.

Since then number theory was used to crack German Enigma codes, and much later figured prominently in public-key cryptography[7]; furthermore, the inter-convertability of mass and energy predicted by special relativity forms the physical basis for nuclear weapons.

He considered that Rolle's theorem, for example, cannot be compared to the elegance and preeminence of the mathematics produced by Évariste Galois and other pure mathematicians, although it is of some importance for calculus.