SB 11.21.3

śuddhy-aśuddhī vidhīyete
 samāneṣv api vastuṣu
dravyasya vicikitsārthaṁ
 guṇa-doṣau śubhāśubhau
dharmārthaṁ vyavahārārthaṁ
 yātrārtham iti cānagha
Synonyms: 
śuddhi — purity; aśuddhī — and impurity; vidhīyete — are established; samāneṣu — of the same category; api — indeed; vastuṣu — among objects; dravyasya — of a particular object; vicikitsā — evaluation; artham — for the purpose of; guṇa-doṣau — good and bad qualities; śubha-aśubhau — auspicious and inauspicious; dharma-artham — for the purpose of religious activities; vyavahāra-artham — for the purpose of ordinary dealings; yātrā-artham — for one’s physical survival; iti — thus; ca — also; anagha — O sinless one.
Translation: 
O sinless Uddhava, in order to understand what is proper in life one must evaluate a given object within its particular category. Thus, in analyzing religious principles one must consider purity and impurity. Similarly, in one’s ordinary dealings one must distinguish between good and bad, and to insure one’s physical survival one must recognize that which is auspicious and inauspicious.
Purport: 

In religious activities, ordinary dealings and personal survival one cannot avoid value judgements. Morality and religion are perennial necessities in civilized society; therefore distinctions between purity and impurity, piety and impiety, morality and immorality must somehow be ascertained. Similarly, in our ordinary, worldly activities we distinguish between palatable and tasteless food, good and bad business, high-class and low-class residences, good and bad friends, and so forth. And to insure our physical health and survival, we must constantly distinguish between what is safe and unsafe, healthy and unhealthy, profitable and unprofitable. Even a learned person must constantly distinguish between good and bad within the material world, but at the same time he must understand the transcendental position of Kṛṣṇa consciousness. Despite one’s careful calculation of that which is materially healthy and unhealthy, the physical body will collapse and die. Despite careful scrutiny of the socially favorable and unfavorable, one’s entire social milieu will vanish with the passing of time. In the same way, great religions arise and disappear in the course of history. Thus mere religiosity, social and financial expertise or physical fitness cannot award the actual perfection of life. There is a transcendental good beyond the relative good of the material world. Any sane person accepts the practical and immediate necessity of material discrimination; yet one must come ultimately to the transcendental stage of Kṛṣṇa consciousness, where life is eternal, full of bliss and knowledge. Lord Kṛṣṇa, in His elaborate teachings to Śrī Uddhava, is gradually clarifying the transcendental position of Kṛṣṇa consciousness beyond the endless variety of material good and evil.