Впрочем, до чего мы достигли, так и должны мыслить и по тому правилу жить.
Only let us live up to what we have already attained.
Only let us hold true to what we have attained.
however, let us keep living by that same standard to which we have attained.
But we must hold on to the progress we have already made.
Nevertheless, whereto we have already attained, let us walk by the same rule, let us mind the same thing.
Nevertheless, to the degree that we have already [e]attained, let us walk by the same [f]rule, let us be of the same mind.
But whereto we have attained, [let us] walk in the same steps.