Yoga Sutras 4.15

Patanjali, explained by Swami Vivekananda

वस्तुसाम्ये चित्तभेदात्तयोर्विभक्तः पन्थाः ॥

vastusāmye cittabhedāttayorvibhaktaḥ panthāḥ

Since perception and desire vary with regard to the same object, mind and object are of different nature.

In plain words: Different people see and want the same thing in different ways. This shows the world is real and separate from our minds, not just our imagination.

Yoga Sutras 4.15

Ask the Swami about this

Swami Vivekananda explains

That is, there is an objective world independent of our minds. This is a refutation of Buddhistic Idealism. Since different people look at the same thing differently, it cannot be a mere imagination of any particular individual.