Yōga Sūtra 2.18

प्रकाशक्रियास्थितिशीलं भूतेन्द्रियात्मकं भोगापवर्गार्थं दृश्यम्।

prakāśakriyāsthitiśīlaṁ bhūtēndriyātmakaṁ bhōgāpavargārthaṁ dr̥śyam।

[प्रकाश क्रिया स्थिति शीलं भूत इन्द्रिय आत्मकं भोग अपवर्गार्थं द्रुश्यम्।
prakāśa = illumination; kriyā = action; sthiti = state; śīlaṁ = character; bhūta = elements (five: water, fire, taste, ether, earth); indriya = senses; ātmakaṁ = driven by; bhōga = experience; apavargārthaṁ = for the purpose of fulfillment; druśyam = observed sensual percept of the scene;]

The observed sensual percept of the scene is for the purpose of fulfillment, experience and is driven by senses. It (the observed picture) is made of light, action, state, character, and (five) elements.

Continuing to explain the cause of obstacles, how an observed form, the picture (drushyam), is created is elaborated further. Desire to experience and fulfill and the associated senses are internal agencies that unite with external elements.

Avoid the misery yet to come. The union of observer with the observed is the cause and must be destroyed.