Ah, how things snowball! First, Post book critic Jonathan Yardley writes,''If ever there was a pygmy among giants, it was me.'' Carol Kalish then writes in {Free for All, May 19} to take exception to Yardley's use of the objective case of a pronoun as a predicate nominative.

Next comes William Fogarty, who finds it ironic that Kalish, ''in her eagerness to show off her knowledge,'' completely overlooked an even more monstrous grammatical error by Yardley: his failure to use the subjunctive mood. The sentence should have read, Fogarty insists, ''If ever there were a pygmy among giants, it was I'' {Free for All, June 2.}

What is really ironic is that Fogarty, in his eagerness to show off his knowledge, shows off exactly the opposite. As any competent authority on English usage will explain, the subjunctive mood is used today only in a very few special cases -- notably, to express a wish and to express a contrary-to-fact or hypothetical situation. ''If ever there was a pygmy among giants'' is neither of these. I refer Fogarty to Margaret Shertzer's "The Elements of Grammar" or "Webster's Dictionary of English Usage."

Fogarty did get something right, however. He said that no one is perfect.

-- James L. Nammack

How can The Post justify devoting so much valuable space to letters on grammar and spelling when there are so many more important issues?

The many books on "correct" grammar are merely helpful guides to better communication skills. Who decides what grammar rules or spelling are officially correct? It's not set in stone. New words and phrases and new uses for old words and phrases are part of the art of language and the art must not be stifled by a few scholarly decisions.

The sole purpose of any communication, written or oral, is to convey a message, and it is far more important that the message delivered is correctly interpreted than it is that the message is in a "correct" form.

-- George Woolley