Question: Account for the delicate shades of colour sometimes seen on the inside of an oyster shell. State and explain the appearance presented when a beam of light falls upon a sheet of glass on which very fine equi-distant parallel lines have been scratched very close to one another.
Answer: The delicate shades are due to putrefaction; the colours always show best when the oyster has been a bad one. Hence they are considered a defect and are called chromatic aberration.
The scratches on the glass will arrange themselves in rings round the light, as any one may see at night in a tram car.

A physical theory remains an empty shell until we have found a reasonable physical interpretation.

Another diversity of Methods is according to the subject or matter which is handled; for there is a great difference in delivery of the Mathematics, which are the most abstracted of knowledges, and Policy, which is the most immersed ... , yet we see how that opinion, besides the weakness of it, hath been of ill desert towards learning, as that which taketh the way to reduce learning to certain empty and barren generalities; being but the very husks and shells of sciences, all the kernel being forced out and expulsed with the torture and press of the method.

I do not know what I may appear to the world, but to myself I seem to have been only like a boy playing on the seashore, and diverting myself in now and then finding a smoother pebble or a prettier shell than ordinary, whilst the great ocean of truth lay all undiscovered before me.

I have said that the investigation for which the teeth of the shark had furnished an opportunity, was very near an end... But thereafter, while I was examining more carefully these details of both places and bodies [sedimentary deposits and shells], these day by day presented points of doubt to me as they followed one another in indissoluble connection, so that I saw myself again and again brought back to the starting-place, as it were, when I thought I was nearest the goal. I might compare those doubts to the heads of the Lernean Hydra, since when one of them had been got rid of, numberless others were born; at any rate, I saw that I was wandering about in a sort of labyrinth, where the nearer one approaches the exit, the wider circuits does one tread.

In the mountains of Parma and Piacenza, multitudes of shells and corals filled with worm-holes may be seen still adhering to the rocks, and when I was making the great horse at Milan a large sack of those which had been found in these parts was brought to my workshop by some peasants... The red stone of the mountains of Verona is found with shells all intermingled, which have become part of this stone... And if you should say that these shells have been and still constantly are being created in such places as these by the nature of the locality or by potency of the heavens in these spots, such an opinion cannot exist in brains possessed of any extensive powers of reasoning because the years of their growth are numbered upon the outer coverings of their shells; and both small and large ones may be seen; and these would not have grown without feeding, or fed without movement, and here [embedded in rock] they would not have been able to move... The peaks of the Apennines once stood up in a sea, in the form of islands surrounded by salt water... and above the plains of Italy where flocks of birds are flying today, fishes were once moving in large shoals.

It would indeed be a great delusion, if we stated that those sports of Nature [we find] enclosed in rocks are there by chance or by some vague creative power. Ah, that would be superficial indeed! In reality, those shells, which once were alive in water and are now dead and decomposed, were made thus by time not Nature; and what we now find as very hard, figured stone, was once soft mud and which received the impression of the shape of a shell, as I have frequently demonstrated.

Many Species of Animals have been lost out of the World, which Philosophers and Divines are unwilling to admit, esteeming the Destruction of anyone Species a Dismembring of the Universe, and rendring the World imperfect; whereas they think the Divine Providence is especially concerned, and solicitous to secure and preserve the Works of the Creation. And truly so it is, as appears, in that it was so careful to lodge all Land Animals in the Ark at the Time of the general Deluge; and in that, of all Animals recorded in Natural Histories, we cannot say that there hath been anyone Species lost, no not of the most infirm, and most exposed to Injury and Ravine. Moreover, it is likely, that as there neither is nor can be any new Species of Animals produced, all proceeding from Seeds at first created; so Providence, without which one individual Sparrow falls not to the ground, doth in that manner watch over all that are created, that an entire Species shall not be lost or destroyed by any Accident. Now, I say, if these Bodies were sometimes the Shells and Bones of Fish, it will thence follow, that many Species have been lost out of the World... To which I have nothing to reply, but that there may be some of them remaining some where or other in the Seas, though as yet they have not come to my Knowledge. Far though they may have perished, or by some Accident been destroyed out of our Seas, yet the Race of them may be preserved and continued still in others.

Most of these Mountains and Inland places whereon these kind of Petrify'd Bodies and Shells are found at present, or have been heretofore, were formerly under the Water, and that either by the descending of the Waters to another part of the Earth by the alteration of the Centre of Gravity of the whole bulk, or rather by the Eruption of some kind of Subterraneous Fires or Earthquakes, great quantities of Earth have been deserted by the Water and laid bare and dry.

Of what use are the great number of petrifactions, of different species, shape and form which are dug up by naturalists? Perhaps the collection of such specimens is sheer vanity and inquisitiveness. I do not presume to say; but we find in our mountains the rarest animals, shells, mussels, and corals embalmed in stone, as it were, living specimens of which are now being sought in vain throughout Europe. These stones alone whisper in the midst of general silence.

Science affects the average man and woman in two ways already. He or she benefits by its application driving a motor-car or omnibus instead of a horse-drawn vehicle, being treated for disease by a doctor or surgeon rather than a witch, and being killed with an automatic pistol or shell in place of a dagger or a battle-axe.

The Good Spirit never cared for the colleges, and though all men and boys were now drilled in Greek, Latin, and Mathematics, it had quite left these shells high on the beach, and was creating and feeding other matters [science] at other ends of the world.

To use Newton's words, our efforts up till this moment have but turned over a pebble or shell here and there on the beach, with only a forlorn hope that under one of them was the gem we were seeking. Now we have the sieve, the minds, the hands, the time, and, particularly, the dedication to find those gems—no matter in which favorite hiding place the children of distant worlds have placed them.
[Co-author with Dava Sobel.]

Why are the bones of great fishes, and oysters and corals and various other shells and sea-snails, found on the high tops of mountains that border the sea, in the same way in which they are found in the depths of the sea?

[An] old Pythagorean prejudice … thought it a crime to eat eggs; because an egg was a microcosm, or universe in little; the shell being the earth; the white, water; fire, the yolk; and the air found between the shell and the white.