Is it known if there was some weird flipping of [Ei (egg in German) and eye] with [Auge(eye in German) and egg] that happened historically or do you think the apparent similarities are coincidence?
New High German (NHG) Auge and English eye are believed to descend from Proto-Germanic *augan- and Proto-Indo-European *ōkū-.
NHG Ei and English egg are from PG *ajjam- and PIE *ōiom.
These words are not related. The homophony of modern English eye with modern German Ei is accidental. There is no “weird flipping".
Notice the consistent phonetic correspondence between the English -(e)y- and the German -(i)g- or -(i)ch-:
- honey - Honig,
- yester(day) - gestern,
- day - Tag,
- eye - Auge,
The reason for this is the palatalization of -g- in certain Germanic dialects, like English. The same English -y- is also the equivalent of the German -j- or -ie- (as in year - Jahr, etc). Hope this helps!
Egg and Ei (pronounced eye), just like the other pairs above, are forms of the same word. Unlike the others, though, all of which are native to English and derive from an initial Germanic g-form, this one is inherited directly from the Nordic egg, and its original form is actually in y (we know this because otherwise we'd expect Latin ocum instead of ovum, for instance). Apparently, Nordics not only kept the original Germanic k and g intact, but sometimes even legitimate Germanic y became k or g (possibly a hypercorrective tendency).
Here are the entries from DWDS:
Ei n. aus Schale, Eiweiß und Eigelb bestehendes Hühner-, Vogelei, ahd. (8. Jh.), mhd. asächs. mnl. nl. ei, mnd. ey, aengl. ǣg (engl. egg aus dem Anord.), anord. egg, schwed. ägg führen auf germ. *ajjam bzw. (wegen des r- Plurals im Aengl. und im Hd.) auf *ajjaz. Der anlautende Vokal kann auf eine schwundstufige Form (ie. ə) zurückgehen oder Kürzung des im Germ. zu ā gewordenen ie. ō sein, das sich in den Formen verwandter Sprachen findet, griech. ōón (ᾠόν), lat. ōvum, kymr. wy, aslaw. ajьce, russ. jajcó (яйцо). Als Ausgangsformen können für diese Sprachen im wesentlichen ie. *ōu̯i̯om, daraus gekürztes *ōi̯om, und wohl auch *ōu̯om angesetzt werden. Zweifellos besteht eine Verbindung zu ie. *əu̯ei- (oder *au̯(e)i- ?), *u̯(e)i- ‘Vogel’ in aind. vḗḥ, vī́ḥ, lat. avis ‘Vogel’, wahrscheinlich auch griech. aietós (αἰετός) ‘Adler’. Je nach Beurteilung des Ablautverhältnisses im Rahmen der ie. Wortbildung wäre danach Ei ursprünglich ‘das zum Vogel Gehörige’ oder der Vogel das ‘Eiertier’. Anders SCHINDLER in: Die Sprache 15 (1969) 166, der für seinen Ansatz ie. *ō-ə̯ui̯-óm ‘Ei’, eigentl. ‘das beim Vogel Befindliche’, von einer präpositionalen Verbindung (mit ie. *ō ‘nahe bei’, s. Ohnmacht) ausgeht. Schon früh wird ‘Vogelei’ auf die Eier anderer Tiere (Insekten, Reptilien, Fische) sowie allgemein auf die weibliche Keimzelle übertragen. –
Auge n. Organ des Gesichtssinnes. Ahd. ouga (8. Jh.), mhd. ouge stimmt mit asächs. ōga, mnd. ōge, mnl. ōghe, nl. oog, aengl. ēage, (angl.) ēge, engl. eye, anord. auga, schwed. öga, dän. øje, got. augō überein. Die Herleitung von germ. *augan- aus ie. *okū- ‘sehen, Auge’, das sich aus aind. ákṣi, griech. ómma (ὄμμα), Dual ósse (ὄσσε), lat. oculus (s. Okular), aslaw. oko, russ. (älter) óko (око), lit. akìs ‘Auge’ erschließen läßt, ist durch die germ. Lautgestalt erschwert, wird aber doch für wahrscheinlich gehalten. Allgemein nimmt man an, daß der Vokal eines regulär entwickelten germ. *agw- (dieses z. B. noch in ahd. awizoraht ‘augenscheinlich’, um 800, acsiunī ‘äußere Erscheinung’, 9. Jh.) unter dem Einfluß von germ. *auzan- ‘Ohr’, vgl. ahd. ōra und (mit grammatischem Wechsel) got. ausō (s. Ohr), umgebildet wurde. Vielleicht hat dabei auch Ausgleich zwischen verschiedenen Flexionsformen eine Rolle gespielt; vgl. FEIST 364. –
Proto-Indo-European is a reconstructed language, not an attested language. The issue here is not the precise reconstruction of long-lost sounds, but merely the observation that “eye” and “Ei” are not related etymologically.
(By the way, Beekes reconstructs IE *h₂ōui-o for “egg” and *h₃ekw for “eye”.)
This is a synthesis of a few other answers, since I haven't seen any that cover all of the details (and in particular how we ended up with "egg").
As Lucian says (in his excellent and detailed answer),
/g/ in German often corresponds to
/j/ in English, particularly next to a front vowel (
/e/). This is why the 'g' in Auge corresponds to the 'y' in eye.
However, "egg" isn't an inherited Germanic word. English is an interesting case because it mixes lots of words from different languages together. In most cases, when you see a 'g' next to an 'i' or 'e' in English, it was borrowed from somewhere else—even for such common words as give, borrowed from Norse (and displacing the inherited yive)!
"Egg" also comes from the Norse side of the Germanic family tree, which kept 'g' next to 'e' (and sometimes even stuck it in where it didn't used to be), and for a while it co-existed with the inherited word. William Caxton, the first person to use a printing press for English, complained about that word in particular:
And specyally he axyed after eggys. And the good wyf answerde that she coude speke no frenshe. And the marchaunt was angry for he also coude speke no frenshe but wold haue hadde egges and she understode hym not. And thenne at laste a nother sayd that he wolde haue eyren. Then the good wyf sayd that she understood hym we.
What sholde a man in thyse dayes now wryte, egges or eyren, certaynly it is harde to playse every man.
And in particular [the merchant] asked for "eggys". But the good wife answered that she couldn't speak French. And the merchant was angry, for he couldn't speak French either, but wanted "egges", and she didn't understand him. And then at last another person said he wanted "eyren". Then the good wife said that she understood him well.
So what should a man write these days, "egges" or "eyren"? Certainly, it's hard to please everyone!
Once again, the inherited word has a 'y'! The -ren is a plural marker, like in "child-ren"; the singular was ey, which looks very much like the German. But "egges" won out—due to Caxton's printing, partially—and "eyren" faded into oblivion.
(It's also possible that "egg" won because "ey" and "eye" were too similar, and that got confusing! See for example how "ink pen" is displacing "pen" in American dialects that merge "pin" with "pen". But that's speculation, nothing more.)
So as others have said, the similarity of these words is a complete coincidence. If they're related, it's farther back than we can reconstruct, back before Proto-Indo-European.
The question cannot be answered beyond reasonable doubt. The two words egg and eye have different roots, as far as we can see, but we cannot see indefinitely far back.
The derivation for egg can be found in wiktionary as from Proto-Indo-European *h₂ōwyóm "egg", what @Anixx gives as *a̯ōu̯iom and @fdb as *ōiom. The wiktionary entry is well sourced at least. It notes that the reconstruction does not account well for all forms, and relates the theory that it derives from *h₂éwis "bird", perhaps from *h₂ew-.
*h₂ew-, derives quite different senses, importantly "to perceive, see, to be aware of" (deriving e.g. *ear* via *h₂ṓws, audio via *h₂ewis-dʰh₁-, Sanskr avis "before the eyes, openly, manifestly, evidently"). Therefore, the relation between eyes and eggs has to be reconsidered.
For eye on the other hand I don't have that much to say. In wiktionary it's derived from *h₃ekʷ-. The state of the art doesn't know a comparison between *h₃ekʷ- and *h₂ew-.
Eggs and eyes compare well at least in shape and color. Another sense given for *h₂ew- is "to dress, clothe", which (is not sourced, but) might be comparable to *(s)kewH- "to cover"; What I'm getting at is the egg-shell, of course, which is reasonable if Ger. Schale appears in sich in Schale werfen "to dress fine", and if the Proto-Germanic root *skal glossed "testicles" is to be believed--eggs is a euphemism for the nuts in many languages. In general, egg is a figurative name for things bearing creation (the female ova, the philosopher's egg?). I did at first assume that *h₂ōwyóm in fact meant "chicken egg", but I have no clue where *-yóm alone came from. Even if it was in fact a productive suffix, I would consider that the suffix had to come from somewhere. I suppose that *-yom relates to *oyn- "1", perhaps as clitic pronoun. But I also think oinkology rather refers to pigs oink oink (´・(oo)・｀) so ymmv
coming up empty for derivation and phonology
There is no conusion, simply because the comparative method can only reconstruct the latest form of PIE to the exclusion of irregular developments and thus to the exclusion of spurious substrata and early adstrata, which have to be expected however for aggriculture and pastoralism.
The superficial similarities in the notation are less pronounced if opting for @fdb's and @Anixx's preferred forms, anyhow.