Preheat oven to 350°F.
Butter an 8 1/2 X 4 1/2 X 3-inch loaf pan, and line bottom with ungreased parchment paper.
(Wax paper may be substituted.) In a medium-size bowl, sift together whole wheat pastry flour, unbleached white flour, baking powder, baking soda, and mace.
In the large bowl of an electric mixer, beat butter until fluffy.
Add honey in a slow stream, then eggs, 1 at a time, and vanilla.
Do not rush this stage, but beat thoroughly after each addition.
Add flour mixture in 4 additions, beating just enough to blend each time.
Spoon batter into prepared pan, and bake on middle shelf of oven for 45 to 50 minutes.
If cake browns before it's done, lay a sheet of aluminum foil loosely over the top as it bakes.
Do not test until cake has risen and split; the split should not appear moist.
A cake tester or food pick inserted into the center should come out clean and dry.
Cool cake in pan on a wire rack until it can be handled.
Remove from pan, and cool completely.
Do not remove parchment paper until cake is sliced.