[Footnote 1:  Epist. 49, and in his De Brevitate Vita.]

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No. 94 Monday, June 18, 1711 Addison.

      ’...  Hoc est
      Vivere bis, vita posse priore frui.’

      Mart.

The last Method which I proposed in my Saturday’s Paper, for filling up those empty Spaces of Life which are so tedious and burdensome to idle People, is the employing ourselves in the Pursuit of Knowledge.  I remember Mr. Boyle [1] speaking of a certain Mineral, tells us, That a Man may consume his whole Life in the Study of it, without arriving at the Knowledge of all its Qualities.  The Truth of it is, there is not a single Science, or any Branch of it, that might not furnish a Man with Business for Life, though it were much longer than it is.

I shall not here engage on those beaten Subjects of the Usefulness of Knowledge, nor of the Pleasure and Perfection it gives the Mind, nor on the Methods of attaining it, nor recommend any particular Branch of it, all which have been the Topicks of many other Writers; but shall indulge my self in a Speculation that is more uncommon, and may therefore perhaps be more entertaining.

I have before shewn how the unemployed Parts of Life appear long and tedious, and shall here endeavour to shew how those Parts of Life which are exercised in Study, Reading, and the Pursuits of Knowledge, are long but not tedious, and by that means discover a Method of lengthening our Lives, and at the same time of turning all the Parts of them to our Advantage.

Mr. Lock observes, [2]

’That we get the Idea of Time, or Duration, by reflecting on that Train of Ideas which succeed one another in our Minds:  That for this Reason, when we sleep soundly without dreaming, we have no Perception of Time, or the Length of it whilst we sleep; and that the Moment wherein we leave off to think, till the Moment we begin to think again, seems to have no distance.’

To which the Author adds,

’And so I doubt not but it would be to a waking Man, if it were possible for him to keep only one Idea in his Mind, without Variation, and the Succession of others:  And we see, that one who fixes his Thoughts very intently on one thing, so as to take but little notice of the Succession of Ideas that pass in his Mind whilst he is taken up with that earnest Contemplation, lets slip out of his Account a good Part of that Duration, and thinks that Time shorter than it is.’

We might carry this Thought further, and consider a Man as, on one Side, shortening his Time by thinking on nothing, or but a few things; so, on the other, as lengthening it, by employing his Thoughts on many Subjects, or by entertaining a quick and constant Succession of Ideas.  Accordingly Monsieur Mallebranche, in his Enquiry after Truth, [3] (which was published several Years before Mr. Lock’s Essay on Human Understanding) tells us, That it is possible some Creatures may think Half an Hour as long as we do a thousand Years; or look upon that Space of Duration which we call a Minute, as an Hour, a Week, a Month, or an whole Age.