INTRODUCTION. 
7 
expanse which now spreads out in purest azure overhead ! He 
sees the limits of the mist that often well-nigh blocked his path, 
and still envelopes his less nimble fellow-travellers ; whilst at 
his feet he many provinces and departments, all grouped in 
harmony and constituting Nature’s realm. 
What next ! 
Shall he, exhausted, lie him down and rest upon the summit ? 
contemplate with indifference the fruitless efforts of those who 
seek to follow in his track ? or smile contemptuously upon the 
ignorant flounderers in the pools below ? 
No ! no ! If he but raise his head and gaze into the infinite 
blue dome above, he will perceive the approving Eye that 
watched him in his upward course, and will obtain a glimpse, 
however faint, of the Creator- Sovereign of the realms below. 
To Him he should direct the attention of his fellow-labourers 
still toiling up the heights, and thus encourage them once more 
to persevere. 
He should not plume himself upon his own successes; but 
should employ them for the good of others. This is the high 
prerogative of every advocate of scientific truth. 
