MEMOIR OF SWAMMERDAM. 
33 
ceive,” (alluding to the minuteness of fern seeds, and 
the mechanism employed to disperse them,) “ with 
what rapidity they may be wafted about by the wind, 
so as to account for these plants being found on the 
tops of the highest trees, and on walls, wliereyer 
they can find mould enough to take root in. 
“ The great obscurity of the human understanding 
is clearly proved by this observation, for, if it were 
not very dark indeed, how could it, during so many 
ages, deny that this plant had either seeds or flowers ? 
insomuch that it was one of the first errors taught 
young people in books, as well as heard in conversa- 
tion. We ought, therefore, to thank the Sun of 
divine grace, and true fountain of all useful know- 
ledge, that we are at last so happy as to attain more 
just notions of this matter. Should not this mistake 
teach us modesty in our opinions and our judgment 
upon many other occasions, seeing upon this the 
most penetrating geniuses have all gone astray ? If 
we are so liable to mistakes in regard to things that 
lie open to our inspection, what are we to say of our 
opinions of things that are invisible? How many 
idle notions are formed on such subjects ! how many 
sensei ess conceits, with which, however, we sometimes 
suffer ourselves so far to be deluded that we make 
nothing of injuring, both in character and person, 
those who happen to be of a contrary opinion ! It is, 
therefore, absolutely necessary that we should always 
distrust ourselves and act with the greatest circum- 
spection. In our present wretched condition, we 
are surrounded with ignorance on every side, and 
o 
