Jefferson Wilson wrote:

> [...]
> Anyway, based on some earlier comments I've been considering
> revising the subject/object distinction.  I'd like to know what
> the difference is between subject/object and agent/patient.

"Subject" and "object" are syntactic notions which do not apply
well to some languages.  In the examples:

(1) The child threw the ball.

(2) The child sang.

(3) The ball fell.

the subjects are "the child", "the child" and "the ball",

"Agent" and "patient" are *semantic* roles.  An agent is an
entity which performs an action, a patient is one which
undergoes an event.  In (1) and (2), "the child" is the agent.
In (3), there is *no* agent - "the ball" is subject but not
agent.  In (1) and (3), "the ball" is the patient; (2) does
not involve a patient.

>       What
> other distinctions like this can people tell me about?  One thing
> I'm considering in particular is a distinction between volitional
> (people) and non-volitional (rocks) subjects, though I'm not
> exactly sure where to draw the line between the two.

You may want to look at the degrees of volition in my conlang
Old Albic, a language which distinguishes between agent and
patient rather than subject and object.  I posted the grammar
last year here, it can be easily accessed via the page

Look for "Case" under "Nominal Morphology" and for "Degrees of
volition" under "Syntax".

(Since then, I have changed some minor details, but these changes
only concern the phonetic shape of some morphemes; the structure
of the language has remained the same.)