John Edwin Sandys, A History of Classical Scholarship
, vol. 2 (Cambridge: Cambridge University Press, 1908), pp. 209-210:
Casaubon lives in his Letters and in his Ephemerides, a Latin journal interspersed with Greek, recording his daily reading and his reflexions for the last seventeen years of his life. When he has read continuously for a whole day, from early morn till late at night, he gratefully records the fact in the words: hodie vixi.
That is, "Today I have lived." See also Mark Pattison, Isaac Casaubon, 1559-1614
, 2nd ed. (Oxford: Clarendon Press, 1892), p. 92:
Casaubon anxiously compares the hours spent in his study with those bestowed on any other occupation. Unless the first greatly preponderate, he is unhappy. When the claims of business or society have taken up any considerable part of the day, his outcries are those of a man who is being robbed. When he has read continuously a whole day, from early morning till late at night, 'noctem addens operi,' he enters a satisfactory 'to-day, I have truly lived,' 'hodie vixi.' Taking some entries of the first period, we have such as the following:—
'To-day I began my work very early in the morning, notwithstanding my having kept it up last night till very late.'
'Nearly the whole morning, and quite all the afternoon perished, through writing letters. Oh! heavy loss, more lamentable than loss of money!'
'To-day I got six hours for study. When shall I get my whole day? Whenever, O my Father, it shall be thy will!'
'This morning not to my books till 7 o'clock or after; alas me! and after that the whole morning lost; nay, the whole day. O God of my salvation, aid my studies, without which life is to me not life.'
'This morning, reading, but not without interruption. After dinner, however, as if they had conspired the destruction of my studies, friends came and broke them off.'
'This morning a good spell of study. After dinner friends, and trifling talk, but very bothering; at last got back to my books.'
'To-day, though far from well, got eight hours for my books.'