 Another major goal of the book is to argue for the notion that all certain or “apodictic” (sometimes spelled “apodeictic”) scientific inference is the same in kind. Again, although Lange does not agree with Herbart that a naturalistic description of thought can capture the necessity of scientific proofs, he disagrees with the notion that only derivation from a priori principles yields certain knowledge. The year after Lange’s book appeared, J. A. Stewart reviewed the work in Mind, saying: