Based on the context of the excerpt the best definition for larded is

imparadis't in one anothers arms  

the happier eden, shall enjoy their fill  

of bliss on bliss, while i to hell am thrust,  

where neither joy nor love, but fierce desire,  

among our other torments not the least,  

still unfulfill'd with pain of longing pines;  

yet let me not forget what i have gain'd  

from their own mouths; all is not theirs it seems:  

one fatal tree there stands of knowledge call'd,  

forbidden them to taste: knowledge forbidd'n?  

suspicious, reasonless. why should their lord  

envie them that? can it be sin to know,

showing or having an insensitive and cruel disregard for others. (so basically being heartless)

hope this : )

the central idea is basically saying that juveniles that have committed a crime will not have the same consequences as the   adults that have. they will have a softer punishment than what the adults have that is harsh in some ways.