Vertically means that every class connected to the next class is connected to every class throughout the semester around a spiral.

纵向意味着每一节课都和下一节课有关系,和整个学期内的每一节课都有关系，呈一个螺旋状。

哈佛公开课 - 幸福课课程节选

Remember I talk those of you who were here the first time: this course is built like a spiral Everything is intra-connected, what I talked about in the first class is connected to what I'm going to talk about today, is going to be connected to lecture 19.

记得一开始我就跟你们说过：,这课程就像个螺旋,内部的一切都是相关的，第一节课讲到的内容,与今天要谈的课题有关，也和第19课有关。

哈佛公开课 - 幸福课课程节选