साधनान्यत्र चत्वारि कथितानि मनीषिभिः ।येषु सत्स्वेव सन्निष्ठा यदभावे न सिध्यति ॥ १८ ॥
In plain words
The sages named four essential qualifications for this path. With them, true steadiness in the goal happens; without them, it simply doesn't.
Close to the Sanskrit
The wise have declared that the means here are four, only in the presence of which steadfastness [in the goal] is accomplished, and in whose absence it does not succeed.