Making a preliminary dictinction between contemporary theatre and non-contemporary theatre, this article draws the limits of the twofold field of investigation for a theatrical genetics in process. In so doing, it underlines more particularly the inquiries and stakes of the genetic analysis of non-contemporary theatre; that is, the theatre antedating the age of the stage director. Relying on a body of significant documents, it puts forward some possible ways of gathering, preserving and interpreting heterogeneous, uncertain and unstable tracks discarded in the outburst of creations which were then little concerned about their preservation. Lastly, a third part brings out the conditions for possible methods of analysis which, by pairing the genetic study of the text and the stage, try to evade the traps of parcelling, of what is aleatory and mobile, in order to retrieve the theatre's creative processes.