妙法蓮華經玄贊 2.7

2.7

Furthermore, there are two kinds of non-retrogression: first, non-retrogression regarding what has already been attained, which is obtained at the first stage; second, non-retrogression regarding what has not yet been attained, which is obtained only at the eighth stage. Since unsurpassed right awakening is a dharma not yet attained, from the eighth stage onward they can be non-retrogressing: with minds yearning for right awakening, they advance without wavering, spontaneously advancing in the swift current of dharmas, which is called non-retrogressing; here "not retrogressing" is synonymous with "not turning back."