  Yet why then did Moore think that the analysis of propositions was so important? In part his motivation derives from his acceptance of a principle which Russell had introduced — that ‘every proposition which we can understand must be composed wholly of constituents with which we are acquainted’ (Russell 91). For this principle motivates the ‘sense-datum analysis’ of perception to which he devoted so much attention and which I shall discuss in a moment. In addition, when explaining the importance of philosophical analysis, he emphasized the importance of getting clear what is at issue in some debate; but an issue which he himself was not clear about was that of the implications of an analysis. In his early writings he took the view that in so far as the analysis of a proposition clarifies it, it also clarifies its ontological implications; thus he then held it to be an objection to a phenomenalist analysis of propositions about material objects that the analysis calls into question the existence of such objects. But he later took the opposite point of view, maintaining that a phenomenalist analysis just provides an account of what their existence amounts to. In between these two positions, in his 1925 paper ‘A Defence of Common Sense’ (which I discuss further below), Moore had held that what the sense-datum analysis of perception shows is that sense-data are the ‘principal or ultimate subject&lt;s&gt;’ (128) of propositions about perception. This remark, I think, reflects the true importance of philosophical analysis for Moore: its importance for him is metaphysical in so far as it reveals the ‘ultimate’ substances which are the subjects of our ordinary common sense thought and talk.