  The complex energies of the three-body resonances for one infinitely heavy
particle and two non-interacting light particles are the sum of the two
contributing two-body complex resonance energies. The bound state of a
Borromean system originates from a resonance when the third interaction is
introduced, a finite mass is allowed and proper angular momentum coupling is
included. The relative importance of these contributions are investigated and
the resulting structure of Borromean systems are traced back to the two-body
continuum properties. The $0^+$ and $2^+$ states in $^{6}$He result from
neutron-core p-states and the ground and first excited state of $^{11}$Li
originate from neutron-core $s^2$ and $sp$-states.
