attended to?  This would be a contradiction in terms.  To be in the mind or the understanding simply means “to be understood” or to be known; no one can have an idea without being conscious of it.  Finally, if the attempt be made to explain “originally in the mind” in so wide a sense that it would include all truths which man can ever attain or is capable of discovering by the right use of reason, this would make not only all mathematical principles, but all knowledge in general, all sciences, and all arts innate; there would be no ground even for the exclusion of wisdom and virtue.  Therefore, either all ideas are innate or none are.  This is an important alternative.  While Locke decides for the second half of the proposition, Leibnitz defends the first by a delicate application of the concept of unconscious representation and of implicit knowledge, which his predecessor rejects out of hand.

[Footnote 1:  According to Fox Bourne this first book was written after the others.  Geil (Ueber die Abhaengigkeit Lockes von Descartes, Strassburg, 1887, chap, iii.) has endeavored to prove that, since the arguments controverted are wanting in Descartes, the attack was not aimed at Descartes and his school, but at native defenders of innate ideas, as Lord Herbert of Cherbury and the English Platonists (Cudworth, More, Parker, Gale).  That along with these the Cartesian doctrine was a second and chief object of attack is shown by Benno Erdmann in his discussion of the treatises by G. Geil and R. Sommer (Lockes Verhaeltnis zu Descartes, Berlin, 1887) in the Archiv fuer Geschichte der Philosophie, ii, pp. 99-121.]

Locke’s positive answer to the question concerning the origin of ideas is given in his second book.  Ideas are not present in the understanding from the beginning, nor are they originated by the understanding, but received through sensation.  The understanding is like a piece of white paper on which perception inscribes its characters.  All knowledge arises in experience.  This is of two kinds, derived either from the external senses or the internal sense.  The perception of external objects is termed Sensation, that of internal phenomena (of the states of the mind itself) Reflection.  External and internal perception are the only windows through which the light of ideas penetrates into the dark chamber of the understanding.  The two are not opened simultaneously, however, but one after the other; since the perceptions of the sensible qualities of bodies, unlike that of the operations of the mind itself, do not require an effort of attention, they are the earlier.  The child receives ideas of sensation before those of reflection; internal perception presupposes external perception.