Not yet reviewed by Pith; the record is open.

It has been a long-standing challenge to accurately predict the properties of light nuclei and nuclear matter simultaneously in nuclear $ab\ initio$ calculations. In this Letter, we develop the relativistic quantum Monte Carlo methods for the nuclear $ab\ initio$ problem, and calculate the ground-state energies of $A\leq4$ nuclei using the two-nucleon Bonn force with an unprecedented high accuracy. For $A=3,4$ nuclei, the present relativistic results significantly outperforms the nonrelativistic results with only two-nucleon forces. Combining the present results for light nuclei and the previous results for nuclear matter with the same Bonn force, a correlation between the properties of light $A\leq4$ nuclei and the nuclear saturation is revealed, and both systems are well described simultaneously, even without introducing three-nucleon forces. This provides a quantitative understanding of the connection between the light nuclei and nuclear matter saturation properties, which has been an outstanding problem in nuclear $ab\ initio$ calculations for decades.