Comparative constitutional law analyses often engage, in some way, in constitutional theorising. For example, they may identify a similar phenomenon or idea present in different jurisdictions and seek to capture it by introducing a new concept or category. In some cases, the limits created by the language barriers we are all subject to can lead to the “invention” of concepts that have existed in some form in jurisdictions we are not able to study. These concepts can then take a life of their own, with the result that not only their connections with older constitutional traditions are obscured, but the possibility of understanding them in alternative ways are diminished. This paper illustrates this problem through an analysis of the basic structure doctrine and the notion of constitutional identity’s connections to the doctrine of the historical constitution, long present, for example, in Spanish constitutional discourse.