So knowing Kṛṣṇa is not so easy thing. Therefore Kṛṣṇa says, manuṣyāṇāṁ sahasreṣu kaścid yatati siddhaye (BG 7.3). First of all you become siddha, perfect. Perfect means perfect knowledge. That is called siddha. And another siddha means very powerful, master of all yogic perfection. That is also siddha. Yogic perfection, eight kinds of perfection,
- animā-laghimā-prāptiḥ
- prākāmyaṁ mahimā yathā
- īśitvaṁ ca vaśitvaṁ ca
- tathā kāmāvasāyitā
So they obtain eight kinds of siddhis. They are also called siddhas. From material point of view, a perfect yogi can counteract anything, and whatever he likes, he can do. That is called siddhi, aṣṭa-siddhi. But still, he is not as siddha as Kṛṣṇa. Kṛṣṇa's name is Yogeśvara. He is the master of all the yogis.