When discussing poder
we have to keep in mind that there is a difference in
Spanish between something that is learned and an ability
that just is there. This is usually not so clear in
English even though we are able to differentiate
the same way. Have a look at these sentences they are
totally different if you think about it.
Example
I can see. (I have eyes that work fine)
I can write. (I know how to write because
I learned it)
The first sentence does not describe the result of
a learning process.
The second sentence describes exactly this result of
a learning process.
Example
Él sabe
escribir, pero de momento no puede.
= He can (knows how to) write but at the
moment he is not able to.
can can be translated
with poder but
only in the meaning of being
able (or not being able to) without a learning
process involved. can is translated
with saber only
in the meaning of to know how
to including a learning process.
To keep up this difference more clearly we distinguish between poder = to be able to and saber = can (to know how to).
example
Sabe escribir.
= He can write (He knows how to write). Sé conducir.
= He can drive a car (He knows how to drive
a car). Sabemos español.
= We know Spanish.
Puedo comer. =
I am able to eat eat.
Podemos dormir. = We am able to sleep. Podéis ir.
= You are able to go.
Sentences like Sabemos dormir
or Sé ver
are pure nonsense. Nobody would say I
know how to see because
it's not a question of learning to see. Of course we
could start - once again - a philosophical discussion
about the sentence "No sabe ver". This sentence
means that due to non-existing education the person
doesn't know to see (to appreciate) the beauty of art
or live or a landscape. He would have to read Marcel
Proust to learn how to see. However back to Spanish
grammar.