ON Tllli NOTION OF INFINITY 213
tinuity' used in mathematics. One is a supposedly 'highgrade' continuity; the other, supposedly, is a 'lowgrade' continuity, which is called 'compactness' or 'density', with the eventual possibility of gaps. I am purposely using rather vague language, since these fundamental notions are now being revised, with the probability that we shall have to be satisfied with 'dense* or 'compact' series and abandon the older, perhaps delusional, 'highgrade' continuity. It is interesting to note that the differential and integral calculus is supposedly based on the 'highgrade' continuity, but the calculus will not be altered.if we accept the 'lowgrade' compactness, all of which is a question of an A ororientation. Vague feelings of 'infinity' have pervaded human s.r as far back as records go. Structurally, this is quite natural because the term infinity expresses primarily a most important semantic process. The majority of our statements can also be reformulated in a language which explicitly involves the term 'infinity'. An example has been already given when we were speaking about the universal propositions which were supposed to be of permanent validity, in other language, valid for 'infinite numbers of years'. We see how the trick is donea vague quasiqualitative expression like 'permanent' or 'universal' is translated into a quantitative language in terms of 'numbers of years'. Such translation of qualitative language into quantitative language is very useful, since it allows us to make more precise and definite the vague, primitive structural assumptions, which present enormous semantic difficulties. This brings to our attention more clearly the structural facts they supposedly state, and aids analysis and revision. In many instances, such translations make obvious the illegitimacy of the assumptions of 'infinite velocities' and so clear away befogging misunderstandings, and beneficially affect our s.r. 


