Lacan on the copulatory verb.
Mr. Heidegger attaches a great deal of importance to the signifier at the
level of the analysis of the word and of conjugation, as it's usually called -
let us more accurately say declension. In German as in French this famous
verb to be is far from being a simple verb and even from being one single
verb. It's evident that the form suis, am, doesn't come from the same root as
es, art, est, is, êtes, [you] are, and as fut, [it] was, nor is there any strict equivalence
to the form été, been. Whereas fut has an equivalent in Latin, as does
suis and the series of est, été comes from another source, from stare. The
distribution is equally different in German where sind, [they] are, is grouped
with bist, art, whereas in French the second person is grouped with the third.
Three roots have been more or less uncovered for all the European languages,
those that correspond to sommes, [we] are, est and fut, which has been compared
with the root phusis in Greek, which is related to the idea of life and
growth. As to the others, Mr. Heidegger insists upon the two aspects, Sten
which would be closer to stare, to stand alone, and Verbahen, to last, to endure,
this sense being nevertheless attached to the source phusis. According to Mr.
Heidegger, the idea of standing erect, the idea of life and the idea of lasting,
enduring, is therefore what an etymological analysis combined with a grammatical 
analysis yields, and it's out of a kind of reduction or of indetermination
cast over these senses as a whole that the notion of being emerges.
I summarize, so as to give you some idea of the thing. I must say that an
analysis of this order is rather inclined to elide, to mask, what Mr. Heidegger
is trying to initiate us into, namely that which is absolutely irreducible in the
function of the verb to be, the copulatory function pure and simple. One
would be mistaken to think that this function is disclosed through a gradual
shift in direction of these various terms.
Pp. 300-1