124 Transactions of the Boy at Microscopical Society. 
This statement depends for its validity upon the assumption 
that the theorists have themselves arrived at the stage of perfec- 
tion, an assumption which has no real foundation. I venture to 
think that there are few persons in the present day who would 
be found bold enough to assert that we have arrived at per- 
fection in any branch of science, least of all in that of microscopy. 
Adopting the view of Sir John Herschel, “ we are not to 
suppose that the field is in the slightest degree narrowed, or 
the chances in favour of fortunate discoveries at all decreased, 
by those which have already taken place ; on the contrary, they 
have been incalculably extended. It is true that the ordinary 
phenomena which pass before our eyes have been minutely ex- 
amined, and those more striking and obvious principles which 
occur to superficial observation have been noticed and embodied in 
our systems of science ; but not to mention that by far the greater 
part of natural phenomena remains yet unexplained, every new 
discovery in science brings into view whole classes of facts which 
would never otherwise have fallen under our notice at all, and 
establishes relations which afibrd to the philosophic mind a con- 
stantly extending field of speculation, in ranging over which it is 
next to impossible that he should not encounter new and unex- 
pected results. ... In whatever state of knowledge we may con- 
ceive man to be placed, his progress towards a yet higher state 
need never fear a check, but must continue until the last existence 
of society.” * 
If perfection is ever to be assumed, one might fairly have 
assumed that the vast amount of research which has been bestowed 
upon the subject of electricity, the many minds that have for many 
years been engaged upon it, and the stimulus of the brilliant pecu- 
niary and other rewards which have been earned, would have 
brought that branch of science, at any rate, to perfection ; and 
yet it is only to-day that the Telephone has been discovered — an 
invention, not the least remarkable feature of which is its extreme 
simplicity. 
Even, therefore, if the theoretical principles of microscopy had 
been apparently as well investigated and as well exhausted, we 
should still not be justified in “ resting and being thankful ” ; 
but when, in fact, no such equivalent work has been done, I 
cannot be accused of any tendency to be over-sanguine if I think 
that the period of perfection in regard to the microscope is certainly 
yet before us. 
The microscope, beyond all other instruments, has already 
suffered greatly from the belief that it could not be improved. 
So splendid a discoverer as Newton asserted that achromatism 
was “ impossible,” though the fact of the achromatism of the eye 
* ‘ Discourse on the Study of Natural Philosophy.’ 
