This inalienable individuality of each essence renders it a universal; for being perfectly self-contained and real only by virtue of its intrinsic character, it contains no reference to any setting in space or time, and stands in no adventitious relations to anything. Therefore without forfeiting its absolute identity it may be repeated or reviewed any number of times. Such embodiments or views of it, like the copies of a book or the acts of reading of it, will be facts or events in nature ( which is a net of external relations ) ; but the copies would not be copies of the same book, nor the readings readings of it, unless ( and in so far as ) the same essence reappeared in them all. Physical obstacles to exact repetitions or reproductions do not affect the essential universality of every essence, even if by chance it occurs only once, or never occurs at all; because in virtue of its perfect identity and individuality, it cannot fall out of the catalogue of essences, where it fills its particular place. If I try to delete it, I reinstate it, since in deleting that I have recognised it and defined it anew, bearing witness to its possessing the whole being which can claim as an essence. There accordingly it stands, waiting to be embodied or noticed, if nature or attention ever choose to halt at that point or traverse it. Every essence in its own realm is just as central, just as normal, and just as complete as any other: it is therefore alway just as open to exemplification or to thought, without the addition or subtraction of one iota of its being.(from The Realm of Essence Section II: The Being Proper to Essences By George Santayana pub.1927)
There accordingly it stands, waiting to be embodied or noticed, if nature or attention ever choose to halt at that point or traverse it. This I understand as the delineation of the notion of trope (tropein - to turn). As we scan the flux the universal pops out. The thought that it can be deleted or deletion might be attempted seems to indicate that it is out there in the flux but that needn't be the case if 'extracting' universals is a power or a capacity that evokes. To alter Plato's aviary that 'bird' does not exist independently in the cage to be whistled up. Looking makes it and calls it up. That this 'bird' is a common or garden one,
- metaphor don't fail me now - is due to our animal nature and evolutionary heritage. This is the famous animal faith.
That is my initial bead on 'the bird' and is probably wrong. By the bye it occurred to me today that while the variety of religious creeds is for the atheist an indication that none of them are right, the variety of philosophical systems which are counter to each other does not likewise imply the uselessness of philosophising.