The Seventh House takes us down even farther than the sixth into the kidneys. The scales and Libra rule this house, and the kidneys, I think you will agree, are very important to the function of the body since you literally cannot live without them.
The Seventh House also has overlaps with marital partners and binding agreements such as those you might need to go to a court of law to enact or resolve.
The essence of this house is "Balance and Justice". If you have many planets in this house, doubtlessly both of those themes will come into view to be experienced.
Another interesting item the Seventh House has some influence over are vehicles. This is likely the case since if your vehicle has tires that are "out of balance" you are not going to enjoy the ride. If it is severely out of balance to the point a wheel flies off, you might just not be journeying anywhere else.
The kidneys we understand to help keep the balance of the body between waste products and purified water. We also know that if our bodies are taxed by some stress that our kidneys are the ones who start pumping various biochemicals cocktails into our system to try to get us ready to restore matters back to normal.
When the balance is primed, there is always something that needs to happen afterwards. The Eighth House will hopefully tell us what.