Most of us do not spend large parts of our lives on boats, but in cars. We cannot, thus, easily generate the kinds of metaphors that must have come naturally to writers from the late 19th and especially early 20th centuries, who would have traveled by boat primarily, and for whom boat and water metaphors would have been the most natural for communicating concepts of motion-against-stability. Today, I suppose, we do not attempt to say anything about motion as it is experienced in cars, or attempt to capture, in a text, the sense of the rushing past of the world on a highway — if anything, we simply show it on film.
There is something about accelerating motion that makes the stability of things, and the status of essences, somewhat questionable to us at a gut level. Everything is hurtling past, and our vision of things is so partial, that, at some level, we question whether intelligibility can be had beyond the traces of impressions that are left to us, which traces often cannot be put together into any whole.
In his work Lord Jim, Joseph Conrad proposes to us, in the mouth of his character Christopher Marlowe, the following judgment about whether he could grasp the personality of the main character, Jim, seen from the outside:
“I don’t pretend I understood him. The views he let me have of himself were like those glimpses through the shifting rents in a thick fog — bits of vivid and vanishing detail, giving no connected idea of the general aspect of a country. They fed one’s curiosity without satisfying it; they were no good for purposes of orientation. Upon the whole he was misleading. That’s how I summed him up to myself after he left me late in the evening. […]” [Joseph Conrad, Lord Jim, ed. Thomas Moser (New York: W. W. Norton, 1996), 49]
It was not until the later in the 19th century that I know of anyone –Baudelaire mentioning the paintings of Constantin Guys— making the increasing acceleration of modern life, and the attempt to extract some traces of stability from within this blur, a theme for reflection, and this sense of rapid motion is, I suppose, nowhere clearer to most people than on trains and boats in the early 20th century.
Similar metaphors could be extended into more general reflections on the nature of knowledge and existence. George Santayana wrote his Scepticism and Animal Faith about twenty years after Conrad’s Lord Jim was published, if my timeline is correct.
Santayana mentions that the existence of something is not another feature to add to the character of what is perceived, but is “something more” is a “complement added to the datum”, and it is added by us. He writes that it is “the finding, the occurrence, the assault, the impact of that being here and now; it is the experience of it.” [Scepticism and Animal Faith (New York: Dover, 1923/1955), 37] He goes on.
The sense of existence evidently belongs to the intoxication, to the Rausch, of existence itself; it is the strain of life within me, prior to all intuition, that in its precipitation and terror, passing as it continually  must from one untenable condition to another, stretches my attention absurdly over what is not given, over the lost and the unattained, the before and after which are wrapped in darkness, and confuses my breathless apprehension of the clear presence of all I can ever truly behold.
Indeed, so much am I a creature of movement, and of the ceaseless metabolism of matter, that I should never catch even these glimpses of the light if there were not rhythms, pauses, repetitions, and nodes in my physical progress, to absorb and reflect it here and there:
as the traveler, hurried in a cloud of smoke and dust through tunnel after tunnel in the Italian Riviera, catches and loses momentary visions of blue sea and sky, which he would like to arrest, but cannot; yet if he had not been rushed and whistled along these particular tunnels, even those snatches, in the form in which they come to him, would have been denied him. So it is the rush of life that, at its open moments, floods me with intuitions, partial and confused, but still revelations; the landscape is wrapped in the smoke of my little engine, and turned into a tantalizing incident of my hot journey. What appears (which is an ideal object and not an event) is thus confused with the event of its appearance; the picture is identified with the kindling or distraction of my attention falling by chance upon it; and the strain of my material existence, battling with material accidents, turns the ideal object too into a temporal fact, and makes it seem substantial. But this fugitive existence which I egotistically attach to it, as if its fate [were] that of my glimpses of it, is no part of its true being, as even my intuition discerns it; it is a practical dignity or potency attributed to it by the irrelevant momentum of my animal life.
Animals, being by nature hounded and hungry creatures, spy out and take alarm at any datum of sense or fancy,  supposing that there is something substantial there, something that will count and work in the world. The notion of a moving world is brought implicitly with them; they fetch it out of the depths of their vegetating psyche, which is a small dark cosmos, silently revolving within. By being noticed, and treated as a signal for I know not what material opportunity or danger, the given image is taken up into the business world, and puts on the garment of existence. Remove this frame, strip off all suggestion of a time when this image was not yet present, or a time when it shall be past, and the very notion of existence is removed. The datum ceases to be an appearance, in the proper and pregnant sense of this word, since it ceases to imply any substance that appears or any mind to which it appears. It is an appearance only in the sense that its nature is wholly manifest, that it is a specific being, which may be mentioned, thought of, seen, or defined, if any one has the wit to do so.
One could probably compile an entire litany of examples of such metaphors across various contexts from this period, if one wished to.
Header image found here.