HARTSOEKER. AUTOBIOGRAPHY [a 
no further publicity. Leeuwenhoek’s own last comment 
on him was’: 
It has come to my ears that Hartsoeker hasn’t much 
of a reputation among the learned: and when I saw that 
he laid claim to untruths, and was stuck-up, I looked 
into his writings no further. 
The foregoing quotations show what some of Leeuwenhoek’s 
contemporaries thought about him: but the best description 
of himself is that unconsciously written by his own hand. His 
own letters are filled with autobiography. On almost every 
page he tells us of his thoughts, his feelings, his everyday 
actions: so that we can now form a very clear and probably 
correct picture of his personality. But it was all done quite 
naturally and ingenuously; for he had no thought, when he 
was writing, that be was often revealing himself rather than 
some ‘“‘mystery of nature”. He sets down his views— 
frequently quite mistaken and even ridiculous views—with 
childish and charming simplicity, and he has no feeling of 
embarrassment in telling the Royal Society the most intimate 
details about his blood, his sweat, or his urine; or about his 
sicknesses or his habits or his little vanities: because he 
always imagines that he is recording matters of scientific 
interest, and he knows by instinct that in registering his 
observations he ought not to withhold any data which may 
possibly have a bearing upon his findings. Yet he always 
presents his results in a way which, despite the imperfections 
of his language and his lack of scientific education, is a model 
for all other workers. He never confuses his facts with his 
speculations. When recording facts he invariably says “I 
have observed . . .”, but when giving his interpretations he 
prefaces them with “but I imagine...” or “I figure to 
myself...” Few scientific workers—or so it seems to me— 
have had so clear a conception of the boundary between 
observation and theory, fact and fancy, the concrete and the 
abstract. 
given Hartsoeker far more credit than he deserves: Dutch writers are better 
informed. (Fontenelle’s Hloge of Hartsoeker will be found reprinted at the 
beginning of the latter's posthumous Cowrs de Physique, 1730.) 
' Send-brief XVIII, 28 Sept. 1715, to Leibniz (Brieven, Vol. IV, p. 170). 
