Roll out the barrel (and other themes)!

I always look for a secondary, underlying theme for my novels... a thread that will weave its way through the story despite plot twists and capricious characters!
In my first book, The Housemaid's Daughter, that theme is music. Ada, the heroine, is a brilliant pianist and music is her inspiration - and refuge. 

In The Girl from Simon's Bay, it is the sea and the forces of nature that forever impact the lives of David and Louise. In The Fire Portrait, the underlying thread is art. For Frances, the heroine, art becomes not just her vocation but also a quietly potent weapon. In The Case Against Fili Du Bois, set in the beautiful Franschhoek Valley with its French heritage estates, I needed to look no further than wine for my subtle theme. I was lucky enough to be given expert help by the owner of an estate and his wine-maker, who led me through the process. I leant about sugar readings, the de-stemming and crushing of the berries, the fermentations, filtrations and periods of maturation that determine the quality and character of the finished product. Fili, the adopted heroine of the novel, immerses herself in the process. It is her way of proving that she belongs at Du Bois Vineyards and that she will carry the traditions of the farm and its workers forward into a bright - yet sometimes uncertain - future... 
For my wine, success would depend on years in the barrel - and a dose of luck:
Would my dark liquid feel inclined to transform itself into a wine that would tell the world I was worthy of being a Du Bois? 
Be strong! I urged myself. Be the best vintage you can be!