Kirchhoff’s first law ($\sum _{ }$i = O) and second law $\sum _{ }$iR =$\sum _{ }$E, where symbols have their usual meanings, are, respectively, based on

According to Kirchhoff’s first law, a junction can act neither as a source of charge nor as a sink of charge. This supports the law of conservation of charges. 

According to Kirchhoff’s second law, the energy per unit charge transferred to the moving charges is equal to the energy per unit charge transferred from them. This supports the law of conservation of energy.