EXPLICIT UFFENBACHIUS. HARTSOEKER 69 
diligence and industry, both in the making of observations 
and in the grinding of lenses, as also in the manufacture 
of the mechanical parts for his microscopia; albeit the 
latter are simple, and badly worked, and for the most 
part roughly fashioned, even the silver not being filed 
smooth in a single one of them. We much wanted to ask 
him why he made so many microscopia, though he would 
not sell any ; but we feared we might get only a Dutch 
answer.. Presumably jealousy lest anybody should get 
hold of microscopes of his pattern, during his lifetime, is 
chiefly at the bottom of this; but there is also some self- 
interest, in that his daughter will one day be able to sell 
them so much dearer, if they cannot be got during his 
own lifetime.” As we were going, both this extraordinary 
man and his daughter earnestly intreated us to tell no 
one that we had been to see him, or seen anything 
there; for the reason that he is old, and tired of being 
pestered, especially by people who are not true lovers of 
learning. .... We were told not only in Delft, but also 
by many foreigners who had waited upon him in vain, 
that he would see no one, still less show people anything : 
and we were therefore greatly rejoiced that we saw so 
many curious things at the house of this extraordinary 
old man. 
One final account of Leeuwenhoek by a man who met 
him must, unfortunately, be mentioned. It was given by 
Hartsoeker,’ an envious fellow-countryman, and was obviously 
*7.e. none: another German pleasantry. 
* As a comment on this unjust remark, it may be recalled that L.’s 
microscopes were not put up for sale until 1747—two years after Maria’s 
death. Cf. p. 320. 
* Nicolaas Hartsoeker (1656-1725), physicist, astronomer, and mathe- 
matician: son of Christiaan Hartsoeker (1626-1683), a minister of the 
reformed Church. He had a variegated career, which is recorded in Dict. 
Sct. méd. (1822), V, 85; N. Ned. Biogr. Woordenb. (1924), VI, 718; and 
elsewhere. In Cwvres Compl. de Chr. Huygens (VIII, 58n) it is stated that 
Hartsoeker was born on 25 March 1654: but this is contradicted by his own 
statement in the Hzt. crit. (1730), p. 43, where he himself gives the date as 
26 March 1656. 
