Take the following schematic:

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![schematic](https://i.sstatic.net/P2Y4J.png)

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You see, in every wire (black lines) there is exactly 1 A flowing, and both the current generators (I1 and I2) are happy because they both see 1 A entering and 1 A exiting.

Just now, we see that the current flowing is 1 A, not 2!

But suppose that we set current generator I2 to 2 A. I2 will do its best to make 2 A flow. Being an ideal current generator, it will collapse the entire universe, if needed, to get the necessary energy to make 2 A flow. The problem is that current generator I1 does the same: being ideal, it will consume the universe to insist that the current flowing "MUST BE 1 ampere!".

If we think that ideal current generators do not exist, the real current flowing, in a real situation, will be something in between the two "nominal currents" of the generators but, again, **not** their sum. Being not ideal, real current generators must leave something to their enemies: for example, for generators of 1A and 2A, the real current could be 1.5A, with each generator giving away something (0.5A) to the enemy.

Probably the concept to stress is that a current generator tries to regulate the current, be it "by pushing it" or "by pulling / braking it", just like a voltage generator tries to regulate voltage. Often we think a voltage generator sources current to keep the voltage, but it can also sink current if we try to raise the voltage.