心脏下面 meaning in Chinese

facies inferior cordis

Just as , twenty years before , she could not believe that the little creature that was lying somewhere under her heart , would one day cry and suck her breast and learn to talk , now she could not believe that the same little creature could be that strong , brave man , that paragon of sons and of men that , judging by this letter , he was now
二十年前她怎么会相信那个在她心脏下面的什么地方生存的小生物，竟会啼哭起来，竟会吸奶和说话，现在从这封信来看，她同样不会相信那个小生物现在竟成为身强体壮的勇敢的男人，竟是众人和子孙的楷模。