Comment by int_19h

Algol (and Pascal) originally did the same thing that C did, except that you used `begin` and `end` instead of `{` and `}` when you needed a compound statement as a branch etc.

Modula changed it so that all structured constructs implicitly introduced a compound statement, and terminated one where appropriate (e.g. on `else`), but this still required some end marker for the last one.

If the question is why `begin` and `end` and not `{` and `}` - for one thing, Algol was designed to be the language you'd write reference implementations of algorithms in for publication, so readability was more important than terseness. For another, it predates ASCII, and not all charsets in use at the time even had `{` and `}` as symbols.