LATER GERMAN PHILOSOPHY 149 



tion by the limits of knowledge. Once we are 

 certain that our objects are strictly ours, are but 

 the framing of our sensations in our a priori forms, 

 we are thenceforth confronted with the limiting 

 notion called the thing-in-itself. The doubt, thence- 

 forward ineradicable, of our power to pass this limit 

 turns into certainty of our impotence to do so, when 

 we find, as Kant shows us, that the attempt must 

 cast reason into systematic contradictions. 



Our knowledge, then, is confined strictly to the field 

 of phenomena ; to knowing, not what is, but only 

 what exists relatively to 11s; and within this field it is 

 further restricted to the tracing of mechanical causa- 

 tion. For, again by Kant's showing, its highest 

 category is action and reaction, and so all the terms 

 conjoined by its synthesis must be extended objects 

 of sense. Hence Du Bois-Reymond's "limits of the 

 knowledge of Nature" become the limits of all 

 knowledge whatever. While, then, our philosophy 

 thus falls into step with natural science, it indeed 

 vindicates to materialism the entire province of 

 Nature, but at the same time excludes materialism 

 from explaining mind. Mind and Nature stand con- 

 trasted as subject and object ; the object, as simply 

 presentation to mind, requires mind as the ground 

 of its existence, and so can never explain mind. 



But the relativity of our knowledge, continues 

 Lange with especial emphasis, reaches wider than 



