The _sensation_ always remains a mere _datum_ for the _understanding_, which alone is capable of apprehending it as the effect of a cause different from itself, which the understanding now perceives as external, _i.e._, as something occupying and filling space, which is also a form inherent in the intellect prior to all experience. Without this intellectual operation, for which the forms must lie ready in us, the perception of an _objective, external world_ could never arise from a mere _sensation_ within our skin. How can it ever be supposed that the mere feeling of being hindered in intended motion, which occurs also in lameness, could be sufficient for this? We may add to this that before I attempt to affect external things _they_ must necessarily have affected me as motives. But this almost presupposes the apprehension of the external world. According to the theory in question (as I have remarked in the place referred to above), a man born without arms and legs could never attain to the idea of causality, and consequently could never arrive at the apprehension of the external world. But that this is not the case is proved by a fact communicated in Froriep’s _Notizen_, July 1838, No. 133—the detailed account, accompanied by a likeness, of an Esthonian girl, Eva Lauk, then fourteen years old, who was born entirely without arms or legs. The account concludes with these words: “According to the evidence of her mother, her mental development had been quite as quick as that of her brothers and sisters; she attained just as soon as they did to a correct judgment of size and distance, yet without the assistance of hands.—Dorpat, 1st March 1838, Dr. A. Hueck.”