To decrease geometrically is this, that in equal times, first the whole quantity then each of its successive remainders is diminished, always by a like proportional part.

And thus the law may be worded:—
The of a commodity to anyone diminishes with every increase in the amount of it he already has.

Take a unit, halve it, halve the result, and so on continually. This gives—1 1⁄2 1⁄4 1⁄8 1⁄16 1⁄32 1⁄64 1⁄128 &c.Add these together, beginning from the first, namely, add the first two, the first three, the first four, &c... We see then a continual approach to 2, which is not reached, nor ever will be, for the deficit from 2 is always equal to the last term added.
...We say that—1, 1 + 1⁄2, 1 + 1⁄2 + 1⁄4, 1 + 1⁄2 + 1⁄4 + 1⁄8, &c. &c.is a series of quantities which continually approximate to the limit 2. Now the truth is, these several quantities are fixed, and do not approximate to 2. ...it is we ourselves who approximate to 2, by passing from one to another. Similarly when we say, "let x be a quantity which continually approximates to the limit 2," we mean, let us assign different values to x, each nearer to 2 than the preceding, and following such a law that we shall, by continuing our steps sufficiently far, actually find a value for x which shall be as near to 2 as we please.

[E]ach several want is limited, and... with every increase in the amount of a thing which a man has, the eagerness of his desire to obtain more of it diminishes; until it yields place to the desire for some other thing, of which perhaps he hardly thought, so long as his more urgent wants were still unsatisfied. There is an endless supply of wants, but there is a limit to each separate want. This familiar and fundamental law of human nature may pass by the name of the Law of Satiable Wants or the Law of Diminishing Utility.
It may be written thus:—
The Total Utility of a commodity to a person (...the total benefit or satisfaction yielded ...by it) increase with every increase in his stock of it, but not as fast as his stock increases. ...[i.e.,] the additional benefit ...from an additional increment of his stock of anything, diminishes with every increase in the stock ...

Something that's everything lacks limitation. There are advantages to not being able to do things. If you had everything you wanted at every moment at your fingertips, then there's nothing. There's no story. It's like Superman being able to bounces hydrogen bombs off of him. The whole series died because he didn't have any flaws. There's no story without limitation.

The following is exactly what we mean by a <small>LIMIT</small>. ...let the several values of x... bea₁ a₂ a₃ a₄. . . . &c.then if by passing from a₁ to a₂, from a₂ to a₃, &c., we continually approach to a certain quantity l [lower case L, for "limit"], so that each of the set differs from l by less than its predecessors; and if, in addition to this, the approach to l is of such a kind, that name any quantity we may, however small, namely z, we shall at last come to a series beginning, say with a_n, and continuing ad infinitum,a_n a_n+1 a_n+2. . . . &c.all the terms of which severally differ from l by less than z: then l is called the limit of x with respect to the supposition in question.

Rather, for all objects and experiences there is a quantity that has an optimum value. Above that quantity, the variable becomes toxic. To fall below that value is to be deprived.

After these came to be relished, an infinite scale of infinites and s (ascending and descending always by infinite steps) was imagined and proposed to be received into geometry, as of the greatest use for penetrating into its abstruse parts. Some have argued for quantities more than infinite; and others for a kind of quantities that are said to be neither finite nor infinite, but of an intermediate and indeterminate nature.

Plato... introduces two infinities, because both in increase and diminution there appears to be transcendency, and a progression to infinity. Though... he did not use them: for neither is there infinity in numbers by diminution or division; since unity is a minimum: nor by increase; for he extends number as far as to the decad.

Past a certain point, more effort doesn’t produce better performance. It sabotages our performance. Economists call this the law of diminishing returns.

[T]he infinite is in capacity. That, however, which is infinite in capacity is not to be assumed as that which is infinite in energy. ...[I]t has its being in capacity, and in division and diminution. ...[I]t is always possible to assume something beyond it. It does not, however, on this account surpass every definite magnitude; as in division it surpasses every definite magnitude, and will be less.

I protest against the use of infinite magnitude as something completed, which is never permissible in mathematics. Infinity is merely a way of speaking

To those who ask what the infinitely small quantity in mathematics is, we answer that it is actually zero. Hence there are not so many mysteries hidden in this concept as they are usually believed to be.

If one does not develop, one goes down. In life, in ordinary conditions everything goes down, or one capacity may develop at the expense of another.