 Early treatises attest to various choices among these models. For instance, Chapa refutes the idealist and the Sautrāntika external-realist models and settles for a Vaibhāṣika-like position, whereas Chumikpa Senggépel (Chu mig pa Seng ge dpal, 13th c.) opts for an idealist framework. Sakya Pandita’s position, shared by Gelukpa authors, is to arrange these positions along a gradual ascending scale; the lowest, the Vaibhāṣika model is refuted in favor of the adoption of the Sautrāntika model, which is itself replaced by an idealist one on a higher scale of analysis.