I have a brain

 It is not in vain

 It is not a stain

 It'll produce grain

With might and main

 From a drop of rain

With a mind serene

 An edifice or a train

 Or any other gain

 If you've been sane

 Not for a moment insane

 Never with it to part

 To produce every art

From the heart of your heart

 Thus, you'll be smart

 And eat the delicious tart