yathaivāvatatāra ha

tat-His; karma-activities; guna-qualities; viryani-and power; kasyapasya-of the son of Kasyapa; maha-atmanah-the great soul; pascat-later; vaksyamahe-I shall describe; adityam-in Aditi; yatha-how; eva-certainly; avatatara-descended; ha-indeed.