>>accomplice, exultant, remorseless, sedate, apprehension, ponderous, revulsion.
>>Sweet is to sour as ... is to light.
>
>If "light" refers to weight and/or nimbleness then you need an approximate opposite meaning heavy and/or plodding. I agree with Dmitry: ponderous is the only viable option.

So... in Genesis 1:3 "Let there be light...." means "let's all shed some extra pounds?"