Help please - completely baffled by quoting

Hi,

I generally consider myself competent with the complexities of quoting but I
can't figure out postgres at all. I've read the manual and it looks very
straightforward but that doesn't accord with my experiences. Here's an
example:

create table temp (a varchar(50));
insert into temp values 'a\'b';
insert into temp values 'a\\b';
insert into temp values 'a\\\'b';

select * from temp returns
a'b
a\b
a\'b

so far so good but what about this:

select * from temp where a like 'a\\\'%'

this should return all strings starting with a\' but it returns nothing!!!

I would expect that these two

select * from temp where a like 'a\\\'b'
select * from temp where a = 'a\\\'b'

should return the same thing. The second one works as expected, but the
first one doesn't return anything.

I'm sure I'm missing something obvious. Thanks in advance for any help.

--- Tim