How do we know what we know? How does the data, the stimulus, the agencies which we experience as reaching us from outside of us become the impressions we interpret as knowledge? The production, giving forth, of knowledge occurs in obscure spaces within each of us, a domain of natural nano-technology which has only the most tenuous, but nevertheless tenable, connection with the meanings which form there.
One thing which distinguishes our knowledge from the data that informs it, is that the knowledge is less dynamic. Knowledge is a practice of integrating data into meaning. Knowledge is the aggregation of this experience, the experience of integrating experiences into models of meaning, testing and adapting these against new experiences. Therefore knowledge invokes memory, the memory not only of experiences but also of the production of knowledge. Knowledge, in this sense, is the always provisional, status quo of a dynamic process.
In Plato’s Theaetetus, Socrates claims that all properties of existence are in motion
“namely, that motion is the cause of that which passes for existence, that is, of becoming, whereas rest is the cause of non-existence and destruction; for warmth or fire, which, you know, is the parent and preserver of all other things, is itself the offspring of movement and friction, and these two are forms of motion. Or are not these the source of fire?” 
Two millennia later, the mathematician Alfred North Whitehead makes a similar claim.
“That ‘all things flow’ is the first vague generalization which the unsystematized, barely analysed, intuition of men has produced. … Without doubt, if we are to go back to that ultimate, integral experience, unwarped by the sophistications of theory, that experience whose elucidation is the final aim of philosophy, the flux of things is one ultimate generalization around which we must weave our philosophical system. ” 
The implication is that knowledge is generated in the fluid interaction between the thing perceived and the perceiving subject. Knowledge can only be said to lose its dynamic property in the historical moment of its application, in an active subject informed by the status quo of the knowledge.
Plato’s Theaetetus recounts a long dialogue between Socrates and the eponymous young scholar on the status of knowledge, with Socrates offering to play the philosophical mid-wife and help Theaetetus “give birth” to the knowledge within him. The dialogue grapples with a famous fragment from Protagoras
πάντων χρημάτων μέτρον ἐστὶν ἄνθρωπος, τῶν μὲν ὄντων ὡς ἔστιν, τῶν δὲ οὐκ ὄντων ὡς οὐκ ἔστιν
“A human being is the measure of all things:
of things which are, that they are, and of things which are not, that they are not”
which Socrates proceeds to interpret as empirical relativism, all the while admitting he is probably misrepresenting what Protagoras meant. A long proto-Cartesian stoicism-infused discussion follows on the unreliability of the senses, with plenty of examples of two people experiencing something together with different perceptions of it. However, one thing can be asserted through all the relativism, that all the perceptions first need to be processed into a language form for the comparison between the two perceivers to take place at all. Operatively this means that empiricism, and therefore, knowledge is always anthropomorphic. Since language is always a convention where meaning is infused into general semantic categories through experience of living users of human language, meaning is also always anthropomorphic. This is another interpretation of Protagoras’ maxim, that we cannot know outside of epistemology overdetermined by human-scale experience of the world.
Our ideas of visuality are informed not by all electromagnetic radiation but by the wavelengths of electromagnetic radiation we perceive as colours of light. Likewise our aurality. Our sense of relative size is informed by how large we are, et c. In this way there can be no non human epistemology, and inversely, the greater Nature, of which human beings can only perceive tiny slices, also includes all human activities, so that “We may not pick and choose. For us the red glow of the sunset should be as much part of nature as are the molecules and electric waves by which men of science would explain the phenomenon” 
What we call science is merely the Latin word for knowledge: scientia, related to scindere, to cut or divide. Science is about taking things apart, measuring them in order to understand how they work. This is not the idle physics of the Greeks, who attempted to understand the essential truth of perceived behaviours and qualities. Science is intrinsically instrumental knowledge, understanding of not of essential truth of behaviours but of what actions will reliably bring about the desired behaviours. Therefore scientific knowledge is always already over-conditioned by human epistemology and human needs. 
The end of Theaetetus in inconclusive. Socrates tests out three definitions of knowledge but none are quite satisfactory, the dialogue breaks off with Socrates leaving for the court where he will eventually be condemned to death. The mortality points to the limit of epistemology, that of the finiteness of human life and of the relationships and exchanges with other humans, the part of the social production of knowledge each person is a part of. Knowledge in oneself is learning from experience, it can remain silent and obscure within the body. As soon as it requires to be exchanged, it must be externalized in explicitly anthropomorphic terms, language, epistemology, words which are determinate, arbitrarily and provisionally fixed and limited, as are particular human capacities, as is human life.
Wisdom is often described as the knowledge of the limits of ones knowledge, an imperfect certainty. Etymologically, wisdom in German is derived from “to see”, “to experience”, and experience comes out (ex-) of taking a risk (as in peril). Acquisition of knowledge entails many risks, not the least of which is that the knowledge acquired is in vain, or for nought. Nevertheless, there is a sense that all experience is valuable though we may not yet know what for.
 Plato. Plato in Twelve Volumes, Vol. 12 translated by Harold N. Fowler. Cambridge, MA, Harvard University Press; London, William Heinemann Ltd. 1921. [153a]
 Whitehead, A. N. ,Process and Reality, New York: Macmillan, 1929, p.317
 Whitehead, A. N. The Concept of Nature, Cambridge: Cambridge University Press; reissued Mineola, NY: Dover Publications, Inc., 2004, Pt 2, Ch. 9, sec. 2
 “…factual ‘discoveries’ (again, according to everyday language) are only discovered as effects or states or properties of manufactured objects or events, they do not refer to natural objects or events at all … ‘discoveries’ made in scientific lab- oratories always discover possible technical procedures. They are concerned with human action, which are successful in the sense that they realize the events states that match the (theoretical or hypothetical) expectation of the experimenter. Discoveries, in short, are always bound up with the scientist’s own proper actions. In other words, only in terms of means-and-ends rationality, lab research can be understood and reconstructed. e scientist makes discoveries by means of his or her inventions. is also holds for all those famous ‘lucky’ discoveries: only if they are reproducible, they count as scientific findings.“ Schmid, G, et al.: (2006) Nanotechnology, Assessment and Perspectives. Springer, Berlin, p.45