PRESIDENTIAL ADDRESS——PRIESTLEY. o 
observation. Like most other generalizations this embodies 
an element of truth, but, if interpreted tceo literally, it is 
apt to be misleading. Burnet, in his history of Karly 
Greek Philosophy, accounts for the origin of the idea in 
the fact that the records we possess are mainly statements 
of results. These by themselves, without any indication 
of the methods by which they were obtained, certainly 
convey the impression that they were dogmatically asserted 
opinions. We know, however, that the Greeks had at their 
disposal a large body of observational facts obtamed by 
the Chaldean astronomers and the Egyptian surveyors. 
Furthermore, there are indications that opinions that at 
first sight appear to be fallacious metaphysical assump- 
tions are, in actual fact, erroneous deductions from 
accurate observation. For example, Xenophanes asserts 
that ‘‘all things are earth and water.’? We might be 
tempted to take this as evidence of the Greek tendency to 
formulate a system of Natural Philosophy based on arbi- 
trary assumption, were it not for the fact that we have 
other records in which it is stated that ‘‘ Xenophanes said 
that a mixture of the earth with the sea is taking place 
and that it is gradually being dissolved by the moisture. 
He says that he has the following proof of this:—Shells 
are found in midland districts and on hills; and he says 
that in the quarries at Syracuse has been found the 
imprint of a fish and of seaweed, at Paros the form of an 
anchovy in the depth of the stone, and at Malta flat 
impressions of all marine animals.’’ 
From this it appears that his assertion was not based 
on mere assumption but was a faulty deduction from 
observation. 
As another example, consider a view of eclipses that 
was current in the early days of Greek Astronomy: The 
sun is a bowl full of burning material which normally has 
its concave side towards us, but which is occasionally 
reversed. This is not a wholly unreasonable interpretation 
of observed phenomena in the infancy of scientific thought ; 
the prominenees visible during a solar eclipse might quite 
well be taken for flames showing over the edge of the 
inverted bewl. 
It is certain, then, that in some cases Greek scientific 
views arose as interpretations of experimental evidence ; 
