Mere Silhouettes

How much detail do you need in a portrait to capture an individual?

These were pre-photographic portraits. Mere silhouettes with an artistic touch at collar and cuff. But how they captured the individuals involved!

A question or two: what are the best lighting conditions to photograph a full body silhouette? Natural light or artificial? Subject between the light source and the backdrop? Light falling on to a screen with the subject in front of it? I'd like to explore these questions but any answers now would be welcomed.