[adrianN]

Every invention is just a combination of existing things with maybe a new twist somewhere. James Watt wasn't the first person to build a steam engine, he just introduced a separate condenser to an existing design.

It's really hard to find a good line of what should constitute a patentable invention. Personally I think that no software should be patentable, ultimately because I don't think that Mathematics should belong to anybody. But I understand that other people see this differently.

[bdowling]

> existing things with maybe a new twist somewhere.

To be valid, a claim must be novel (new) and non-obvious over the prior art. So there absolutely must be a new twist somewhere.

[adrianN]

I can still build a machine entirely from off-the shelf parts, connecting them exactly in the ways they're built to connect to each other, and claim to have invented it.

[bdowling]

If the resulting combination is a machine that is useful, new, and non-obvious, then I'd call that an invention.