The rule is, jam tomorrow and jam yesterday - but never jam today.
As you have invited me, I cannot come, for I have made a rule to decline all invitations; but I will come the next day.
Here is a golden Rule to begin with. Write legibly. The average temper of the human race would be perceptibly sweetened, if everybody obeyed this Rule! A great deal of the bad writing in the world comes simply from writing too quickly.