der Deutsche, etwas Gutes: adjectives turned into nouns

In German an adjective becomes a noun without changing shape: you capitalise it and that is it. der Alte, die Kleine, das Beste, ein Bekannter. And the surprising part: it STILL declines like an adjective, so its ending changes with the case — der Alte, den Alten, dem Alten — even though it is now a noun. After etwas, nichts, viel and wenig it is nominalised as a neuter and takes -es.

The usual slip. Leaving it with no ending as if it were an ordinary noun: der Deutsch. It is not: der Deutsche, den Deutschen, ein Deutscher. The second mistake is forgetting the capital after etwas and nichts: it is etwas Gutes, with a capital G, because there the adjective is no longer an adjective but a name.

Why it catches you out. English cannot do this at all: you have to say «the old man», «something good», with a real noun or a following adjective. So the whole construction is new, and the capital letter looks strange. The upside is that the ending is the one you already learnt for adjectives: no new table.