stems of matters of fact which suffice to determine the
| | measure-relations of space -- the most important system for our present
| | purpose being that which Euclid has laid down as a foundation.  These
| | matters of fact are -- like all matters of fact -- not necessary, but
| | only of empirical certainty;  they are hypotheses.  We may therefore
| | investigate their probability, which within the limits of observation
| | is of course very great ...
|
| He then proceeded to consider separately the noti