Swapping around the three Jewels
This is the way my teachers have explained it:


The Buddha is like a Doctor on who we rely to correctly diagnose our condition and to prescribe a treatment.
The Dharma is like the actual medicine and is thus referred to the supreme jewel or true jewel.
The Sangha is like the nurses who aid us in our treatment and recovery.


Just as we take refuge in our Doctors, Medications and Nurses when we become sick just so we should take refuge in the Buddhas, Dharma, and Sangha to shelter us from the sicknesses of samsara.

That said, the Dharma jewel is considered the Supreme Jewel because it is the actual antidote to our suffering. And we must choose to take our medication. The Buddha cannot force us to take our medicine nor can the Sangha. We must choose to listen to the Doctor's advice and take the actual antidote and listen to the Nurses as they help us take the medicine and recover.