  The historical process of the genesis of the extensive or substance-like
quantities took place in two steps. First, global conservation or
non-conservation was discovered. Only later did it become possible to formulate
the balance locally in the form of a continuity equation. This process can be
clearly seen in energy, momentum, and entropy. After a long and intricate
history, the quantitative description of the local balance has been achieved
for all of the three quantities in a surprisingly short period of time around
the turn of the 19th to the 20th century. The new ideas could have simplified
considerably the teaching of energy, momentum, and entropy. However, in all
three cases, today's language of physics remained essentially the same as it
was at the time when a local balancing was not yet possible.
