Laudator Temporis Acti

Henry David Thoreau, Walden, chapter 1 (Economy):

As for the Pyramids, there is nothing to wonder at in them so much as the fact that so many men could be found degraded enough to spend their lives constructing a tomb for some ambitious booby, whom it would have been wiser and manlier to have drowned in the Nile, and then given his body to the dogs. I might possibly invent some excuse for them and him, but I have no time for it.

Walter Harding, The Variorum Walden (New York: Washington Square Press, 1963), p. 270, n. 161, on this passage:

Emerson in his Journals for August 18, 1852 (VIII, 320), attributes a very similar opinion of the worth of the pyramids to Horatio Greenough. But Greenough apparently made his statement that month, whereas Thoreau's is recorded in his own Journal for April 21, 1852 (III, 454).

Here is Emerson's record of Greenough's remark:

In the old Egyptian, and in the middle age architecture, he sees only "cost to the constituency," prodigious toil of prostrate humanity.

Pace Harding, this doesn't seem to me to be "very similar" to the passage from Walden. There is a greater similarity between Thoreau's criticism of the pyramids and some observations of Dominique Vivant-Denon, Voyage dans la Basse et la Haute Egypte pendant les campagnes du général Bonaparte (1802), p. 97 (tr. Arthur Aitkin):

In reflecting on the object of the construction of the pyramids, the gigantic pride which gave them birth appears more enormous even than their physical dimensions; and one hardly knows which is the most astonishing, the madness of tyrannical oppression, which dared to order the undertaking, or the stupid servility of obedience in the people who submitted to the labour.

Si l'on considere l'objet de la construction des pyramides, la masse d'orgueil qui les a fait entreprendre paroît excéder celle de leur dimension physique; et de ce moment l'on ne sait ce qui doit le plus étonner de la démence tyrannique qui a osé en commander l'exécution, ou de la stupide obéissance du peuple qui a bien voulu prêter ses bras à de pareilles constructions.

Aitkin's translation of this passage from Denon also appeared in an article on the pyramids in The American Penny Magazine and Family Newspaper II.22 (July 5, 1846), pp. 337-339 (at 339). In a letter to Ellen Emerson (July 31, 1849), Thoreau mentions reading the Penny Magazine. Ralph Waldo Emerson mentions Denon in his essays The Conduct of Life and The Man of Letters.

Finally, here is the passage from Thoreau's Journal (April 21, 1852):

We have heard enough nonsense about the Pyramids. If Congress should vote to rear such structures on the prairies to-day, I should not think it worth the while, nor be interested in the enterprise. It was the foolish undertaking of some tyrant. "But," says my neighbor, "when they were built, all men believed in them and were inspired to build them." Nonsense! nonsense! I believe that they were built essentially in the same spirit in which the public works of Egypt, of England, and America are built to-day — the Mahmoudi Canal, the Tubular Bridge, Thames Tunnel, and the Washington Monument. The inspiring motive in the actual builders of these works is garlic, or beef, or potatoes. For meat and drink and the necessaries of life men can be hired to do many things. "Ah," says my neighbor, "but the stones are fitted with such nice joints!" But the joints were nicer yet before they were disjointed in the quarry. Men are wont to speak as if it were a noble work to build a pyramid — to set, forsooth, a hundred thousand Irishmen at work at fifty cents a day to piling stone. As if the good joints could ennoble it, if a noble motive was wanting! To ramble round the world to see that pile of stones which ambitious Mr. Cheops, an Egyptian booby, like some Lord Timothy Dexter, caused a hundred thousand poor devils to pile up for low wages, which contained for all treasure the thigh-bone of a cow. The tower of Babel has been a good deal laughed at. It was just as sensible an undertaking as the Pyramids, which, because they were completed and have stood to this day, are admired.