Anger is a living thing, feed it and it will grow
“Anger is a living thing, feed it and it will grow”
-Darth Sidious
Indeed truer words were never spoken, however I would state that any emotion is a living thing, negative, or positive. Feed any of them and they will grow, fueling you, and any Sith should be mindful to experience the whole spectrum of emotion, not just dwell in one over the other. However the fact is that emotion is a living thing, and if fed long enough it can grow out of the proportion of you to control. It can consume you... Anger turns into uncontrollable rage, Love into obsession, etc... Sith feed off of their emotions, it strengthens them, and their connection, not only to the force (Ki, chi, life, univeral energy..) but to themselves. To truly understand yourself, you must understand your emotions and how they can effect you, you must test the limits of how much you can feed them. Only by knowing ones limits can one surpass them...
This is where your will comes in, for without a powerful will, your emotions can easily control you and make you a slave to them. Anyone who has lost their temper and needlessly and recklessly destroyed things around them in their rage knows this as fact. If you haven't ever lost control of your temper, then refer to DARTH BANE: RULE OF TWO Bane loses his temper and almost destroys his apprentice, once he gained control of himself he saw what waste that would of been, not only of time, but of a precious resource of one so strong in the force to carry on the Sith. Or in the case of Vader attacking Obi Wan from a strategecly disadvantageous position...and we all saw how that went.
Your emotions are fuel, your will must be the furnace that keeps your emotions from consuming you in their flames. If the furnace of your will is not strong enough and you continue to feed your emotions past the point where it erodes your will, then yes, you may have greater power...but for what? Power without focus or goal, is pointless. Power without control, is useless and serves no one, not even yourself. When you can bring together emotion and the will, true use of its power is brought to bear. An intelligent mind, can through the use of will, focus your emotions to a lasers point, making the use of them benificial to you. To do this effectively you must practice. As stated, emotions are living things, without sufficient practice they will continue to feed until they consume that which generated them.
Emotions are the laser, the power, Sith are the lense that focus it, which use the power. Lasers can save lives, such as in operations, or burn holes in things. That however is up to the individuals will to focus and choices they make...So if emotions are the laser and the Sith is the lense, think of the Force (Ki, Chi, Univeral life energy, God, whatever....) as the machine which powers it. So make sure the lense is well forged and focused, your mind, body, and spirit must be forged properly to become a proper lense. Use this knowledge wisely and responsibly.