Here are some various quotes about various aspects of the Force...
"Which brings us up to the films 4, 5, and 6, in which Anakin's offspring redeem him and allow him to fulfill the prophecy where he brings Balance to the Force by doing away with the Sith and getting rid of evil in the universe..." -Lucas
"But if it was force-generated, it could be Force repelled. Luke raised his arms to deflect the bolts. Initially, he was successful- the lightning rebounded from his touch, harmlessly into the walls. Soon, though, the shocks came with such speed and power, they course over and into him. -ROTJ novelization"
"But this was no simple warrior enemy. Dooku's hand shot out toward the charging Jedi, sending forth a Force push as solid as any stone wall, and a burst of blue Force lightning, unknown to the Jedi, charged all about the trapped and lifted Jedi Padawan." -AOTC novelization
"...I had to begin to show that Dooku had these powers similar to what the Emperor had. Sith powers. Dark Side powers...so we do a little bit of the Sith thing in the beginning to get rid of Anakin and let Obi-Wan have his fight." -Lucas
"...to become the most powerful Jedi, and the only way you can really do that is to go to the Dark side because the Dark side is more powerful. If you want the ultimate power you really have to go to the stronger side, which is the Dark side..." - Lucas [AOTC commentary]