First read: Plato, Statesman

The Statesman is an example of how to define a scientific field. The Eleatic Stranger and a young Socrates have gathered to discuss an area of science: the science of the political. The classification of political science goes as follows:

The division between the theoretical and practical is akin to the division between knowledge work and manual labor. The individual contributor is engaged in knowledge work that does not need to be passed off to others, while the manager does. The mathematician is an individual contributor, while the statesman is not, so we climb down the "Manager" node on this tree of science:

The tree in Plato's text is more detailed than the one displayed here, but we see that the division has been made between middle management and upper management. Middle management passes on instructions from elsewhere, while upper management forges and passes on their own instructions. A prophet who passes on the instructions of God to the people is middle management.

Following the none of the "Upper Manager", we see that this science divided into the work of the master-workman and herdsman: the management of non-living things and living things, respectively. Notice, as we go farther down the tree, the more the lines between a practical science and a theoretical science are blurred. The mathematician only needs to worry about abstract objects, but a master-builder, such as an engineer, has to be concerned with the actions of the beings he's controlling in order to be successful. This applies to the herdsman and, with that, the statesman.

Reference: Method and Metaphysics in Plato’s Sophist and Statesman