text:  But (wisely too) passing this over and admitting that there is a distinction (though a very ill-defined one) between the several truths we entertain of this nature; namely that some we find it impossible even in imagination to contradict whilst of others we can suppose it possible that they should cease to be truths--does it follow that different faculties of the mind are engaged in the acquisition of them? Does nothing depend on the nature of the subject itself? "That two sides of a triangle " says Mr Whewell "are greater than the third is a universal and necessary geometrical truth; it is true of all triangles; it is true in such a way that the contrary cannot be conceived