'Preface to the Treatise on the Vacuum' by Blaise Pascal (1662)

A selection from the preface of Blaise Pascal's (incomplete) Treatise on the Vacuum

Pascal's treatise is the source of the famous analogy of humanity with a single individual:

"...not merely individual man advance in the sciences, but all men taken collectively advance in them, as the world grows older; for it is with successive generations of men, as with the different ages of the individual, so that the whole series of individuals, continued throughout the ages, should be considered as one and the same man, persisting always and continually learning." [Pascal, Treatise on the Vacuum (alternate translation)]

Charles Perrault, who wrote the first collection of fairy tales 200 years before the Brothers Grimm, expressed much the same idea when he said that
"the human race ought to be considered as a single eternal man, so that the life of mankind, like that of the individual, has had its infancy, has now its manhood, but will have no decline."

From Kants essay Universal History from a Cosmopolitan View of History (1784):
"...a single man would have to live excessively long in order to learn to make full use of all his natural capacities. Since Nature has set only a short period for his life, she needs a perhaps unreckonable series of generations, each of which passes its own enlightenment to its successor in order finally to bring the seeds of enlightenment to that degree of development in our race which is completely suitable to Nature’s purpose."

And in Toynbee's Study of History (1932), we find:

The continuity of history, to use an accepted phrase, is not a continuity such as is exemplified in the life of a single individual. It is rather a continuity made up of the lives of successive generations, our Western Society being related to the Hellenic Society in a manner comprable (to use a convenient though imperfect simile) with the relationship of a child to its parent.

We find a similar 'allegory' of a man made up of the sum total of individual lives lived up to the present in Jung's 'personification of the Unconscious' contained in his Modern Man in Search of a Soul (1932):

"While consciousness is intensive and concentrated, it is transient and is directed upon the immediate present and the immediate field of attention; moveover, it has access only to material that represents one individuals experience stretching over a few decades. A wider range of "memory" is artifically acquired and consists mostly of printed paper. But matters stand very differently with the unconscious. It is not concentrated and intensive, but shades off into obscurity; it is highly extensive and can juxtapose the most heterogenous elements  in the most paradoxical way.  [...] If it were permissible to personify the unconscious, we might call it a collective human being combining the characteristics of both sexes, transcending youth and age, birth and death, and, from having at his command a human experience of one or two million years, almost immortal. If such a being existed, he would be exalted above all temporal change; the present would mean neither more nor less to him than any year in the one hundredth century before Christ; he would be a dreamer of age-old dreams and, owing to his immeasurable experience, he would be an incomparable prognosticator. He would have lived countless times over the life of the individual, of the family, tribe, and people, and he would possess the living sense of the rhythm of growth, flowering and decay.

It would be positively grotesque for us to call this immense system of experience of the unconscious psyche an illusion, for our visible and tangible body itself is such a system."

These themes can be seen in a 2007 film 'The Man from Earth.' 

In matters in which we only seek to know what the authors have written, as in history, geography, jurisprudence, languages, and especially in theology; and in fine in all those which have for their principle either simple facts or divine or human institutions, we must necessarily have recourse to their books, since all that we can know of them is therein contained, hence it is evident that we can have full knowledge of them, and that it is not possible to add any thing thereto. 7
If it is in question to know who was the first king of the French; in what spot geographers place the first meridian; what words are used in a dead language, and all things of this nature; what other means than books can guide us to them? And who can add any thing new to what they teach us, since we wish only to know what they contain? 8
Authority alone can enlighten us on these... .

It is not the same with subjects that fall under the senses and under reasoning; authority here is useless; it belongs to reason alone to know them. They have their separate rights: there the one has all the advantage, here the other reigns in turn. But as subjects of this kind are proportioned to the grasp of the mind, it finds full liberty to extend them; its inexhaustible fertility produces continually, and its inventions may be multiplied altogether without limit and without interruption…. 10

It is thus that geometry, arithmetic, music, physics, medicine, architecture, and all the sciences that are subject to experiment and reasoning, should be augmented in order to become perfect. The ancients found them merely outlined by those who preceded them; and we shall leave them to those who will come after us in a more finished state than we received them.

  The clearing up of this difference should make us pity the blindness of those who bring authority alone as proof in physical matters, instead of reasoning or experiments; and inspire us with horror for the wickedness of others who make use of reasoning alone in theology, instead of the authority of the Scripture and the Fathers.

...what is more unjust that to treat our ancestors with more deference than they showed to those who preceded them, and to have for them that inviolable respect which they have only merited from us because they had not the like for those who possessed the same advantage over them?…

The secrets of nature are concealed; although she is continually working, we do not always discover her effects: time reveals them from age to age, and although always alike in herself she is not always alike known.      17
  The experiments that give us the knowledge of these secrets are multiplied continually; and as they are the sole principles of physics, the consequences are multiplied in proportion.      18
  It is in this manner that we may at the present day adopt different sentiments and new opinions, without despising the ancients and 3 without ingratitude, since the first knowledge which they have given us has served as a stepping-stone to our own, and since in these advantages we are indebted to them for our ascendency over them; because being raised by their aid to a certain degree, the slightest effort causes us to mount still higher, and with less pains and less glory we fined ourselves above them. Thence it is that we are enabled to discover things which it was impossible for them to perceive. Our view is more extended, and although they knew as well as we all that they could observe in nature, they did not, nevertheless, know it so well, and we see more than they.      19
  Yet it is marvellous in what manner their sentiments are revered. It is made a crime to contradict them and an act of treason to add to them, as though they had left no more truths to be known.      20
  Is not this to treat unworthily the reason of man and to put it on a level with the instinct of animals, since we take away the principal difference between them, which is that the effects of reason accumulate without ceasing, whilst instinct remains always in the same state? The cells of the bees were as correctly measured a thousand years ago as to-day, and each formed a hexagon as exactly the first time as the last. It is the same with all that the animals produce by this occult impulse. Nature instructs them in proportion as necessity impels them; but this fragile science is lost with the wants which give it birth: as they received it without study, they have not the happiness of preserving it; and every time it is given them it is new to them, since the … nature having for her object nothing but the maintenance of animals in a limited order of perfection, she inspires them with this necessary science … always the same, lest they may fall into decay, and does not permit them to add to it, lest they should exceed the limits that she has prescribed to them. It is not the same with man, who is formed only for infinity. He is ignorant at the earliest age of his life; but he is instructed unceasingly in his progress; for he derives advantage, not only from his own experience, but also from that of his predecessors; since he always retains in his memory the knowledge which he himself has once acquired, and since he has that of the ancients ever present in the books which they have bequeathed to him. And as he preserves this knowledge, he can also add to it easily; so that men are at the present day in some sort in the same condition in which those ancient philosophers would have been found, could they have survived till the present time, adding to the knowledge which they possessed that which their studies would have acquired by the aid of so many centuries. Thence it is that by an especial prerogative, not only does each man advance from day to day in the sciences, but all mankind together make continual progress in proportion as the world grows older, since the same thing happens in the succession of men as in the different ages of single individuals. So that the whole succession of men, during the course of many ages, should be considered as a single man who subsists forever and learns continually, whence we see with what injustice we respect antiquity in philosophers; for as old age is that period of life most remote from infancy, who does not see that old age in this universal man ought not to be sought in the times nearest his birth, but in those the most remote from it? Those whom we call ancient were really new in all things, and properly constituted the infancy of mankind; and as we have joined to their knowledge the experience of the centuries which have followed them, it is in ourselves that we should find this antiquity that we revere in others.      21
  They should be admired for the results which they derived from the very few principles they possessed, and they should be excused for those in which they failed rather from the lack of the advantage of experience than the strength of reasoning.

Thus it is that, without contradicting them [the ancient Greeks], we can affirm the contrary of what they say; and, whatever authority, in fine, this antiquity may have, truth should always have more, although newly discovered, since she is always older than all the opinions that we have had of her, and it would be showing ourselves ignorant of her nature to imagine that she may have begun to be at the time when she began to be known.