Why does resonance greatly increase the likelihood of the triple alpha process?

[cragwolf]

Why does "resonance" greatly increase the likelihood of the triple alpha process?

Why does the fact that the combined energy of ⁸Be and ⁴He is (almost) the same as the energy of an excited state of ¹²C greatly increase the probability of that reaction (i.e. ⁸Be + ⁴He → ¹²C + stuff) occurring? Apparently it doesn't have to be exactly the same, but does it make any difference if it's slightly less vs slightly more?

 

[QuantumPion]

All atoms have lower mass than the sum of their parts. This difference is called binding energy, and is the reason why nuclear fusion and fission are exothermic processes. In order for a particular reaction to take place, there must be sufficient energy so that starting product mass + binding energy + kinetic energy = end product mass + binding energy + kinetic energy. If the starting products do not have sufficient mass and kinetic energy to equal the end products, the reaction cannot occur.

Here is a link better explaining binding energy: http://hyperphysics.phy-astr.gsu.edu/hbase/nucene/nucbin.html