More has been written on the fall of Rome than on the death of any other civilization. (2) While scholars are still debating this issue today, most agree that a number of factors led to Rome's demise at the hands of Germanic attackers in 476 A. D. (3) First, Rome was vulnerable to outside attackers because of internal political instability. (4) The Roman constitution did not have a clear law of succession. (5) As a result, each time a ruler died, civil war would break out—killing thousands and causing great political struggle. (6) Another factor that made Rome ripe for conquest was severe economic turmoil. (7) Rome's economy relied heavily upon slave labor. (8) However, years of harsh work and poor living conditions reduced the population of Rome's slaves. (9) Fewer slaves working on farms meant that the empire had fewer goods for trade and less food for its citizens. (10) Rome was also weakened by a lack of manpower. (11) The empire's long borders required more soldiers than were available to protect it from attack. (12) In addition, the need for soldiers abroad meant that there were fewer people to keep peace and order within the empire. QuestionA1. The main idea of this textbook passage is expressed in sentencea. 1.b. 2.c. 4.d. 12.