[senthil_rajasek]

whole spices preserve the essential oils better when whole.

roasting them whole and grinding them before use brings out the flavors since most of the essential oils have not evaporated.

[hnick]

Yep, that's the bit I was missing. I think a lot of us just buy pre-ground so it's important to make that point.

It probably explains why I pour a few tablespoons of cumin in everything (apart from it being great).