People were not necessary for a closed ecosystem to run once stable, but they might be helpful in stabilizing it. 封闭系统一旦进入稳定运行，人类就不是必不可少的部分，不过，他们可能会有助于其稳定。
Dowling points out that excess ink is recirculated within the sealed system, reducing consumption and contamination from lint, dust or dampener fluid. 道林指出，过剩的墨水循环的封闭系统，减少消耗和污染皮棉，尘埃或沮丧液。
